
Class. 
Book- 






ORGANIC CHEMISTRY 



ITS APPLICATIONS 



AGRICULTURE AND PHYSIOLOGY. 



ORGANIC CHEMISTRY 



IN ITS APPLICATIONS 



AGRICULTURE AND PHYSIOLOGY. 

JUSTUS LIEBIG, M.D., Ph.D., F.R.S., M.R.I.A., &c., 
W 

PROFESSOR OF CHEMI9TKY IN THE UNIVERSITY OF GIESSEN. 

EDITED FROM THE MANUSCRIPT OF THE AUTHOR 
By LYON PLAYFAIR, Ph.D. 



FIRST AMERICAN EDITION, 

WITH AN 

INTRODUCTION, NOTES, AND APPENDIX, 



JOHN W. WEBSTER, M.D., 

1 ^ 

PROFESSOR OF CHEMISTRY IN HARVARD UNIVERSITY. 



CAMBRIDGE: 
PUBLISHED BY JOHN OWEN. 

BOSTON, JAMES MUNROE AND COMPANY, AND C. C. LITTLE AND J. BROWN J 
NEW YORK, WILEY AND PUTNAM, AND GEO. C. THORBURN J 
PHILADELPHIA, THOMAS, COWPERTH WAIT, AND COM- 
PANY, AND CARY AND HART ; BALTIMORE, 
CUSHING AND BROTHER. 

1841. 






\ 



% 



Entered according lo Act of Congress, in tiie year 1841, by 

John Owen, 

in the Clerk's Office of llie District Court of tlie District of Massachusetts 



CAMBRIDGE: 

FOLSOM, WELLS, AND THURSTON, 

PBINTEBS TO THE UNIVERSITY. 






CONTENTS. 



INTRODUCTION. 

FIRST ELEMENTS OF CHEMISTRY. 

CHAPTER PAGE 

I. Definitions 1 

II. Affinity — Crystallization .... 15 

Combination 22 

Decomposition .... 25 

III. Laws of Chemical Proportion ... 32 

IV. Theory of Chemical Proportions . . 36 
V. Connexion between the Atomic Weight and 

Volume of a Body ..... 41 

VI. Isomorphism. Catalytism .... 42 

VII. Theory of the Constitution of Salts . 46 

PART FIRST. 

I. On the Chemical Processes in the Nutrition 
OF Vegetables, and the Constituent Ele- 
ments of Plants 53 

II. On the Assimilation of Carbon ... 57 

III. On the Origin and Action of Humus . . 95 

Vegetable Mould 97 

IV. On the Assimilation of Hydrogen . . . 120 

V. On the Origin and Assimilation of Nitrogen 126 
VI. On the Inorganic Constituents of Plants . 147 

VII. The Art of Culture 169 

VIII. On the Interchange of Crops, and of Manure 206 

PART SECOND. 

OF THE CHEMICAL PROCESSES OF FERMENTATION, DECAY, 
AND PUTREFACTION. 

1. Chemical Transformations .... 249 
II. On the Causes which Effect Fermentation, 

Decay, and Putrefaction .... 252 



VI 



CONTENTS. 



III. 
IV. 



V. 

VI. 
VII. 

VIII. 

IX. 
X. 

XI. 



Fermentation and Putrefaction 

On the Transformation of Bodies which do 
NOT contain Nitrogen as a Constituent, 
AND of those in whi(;h it is present . 

Fermentation of Sugar .... 

Eremacausis, or Decay 

Eremacausis, or Decay, of Bodies which do not 
contain Nitrogen : Formation of Acetic Acid 

Eremacausis of Substances containing Nitro- 
gen. Nitrification 

On Vinous Fermentation: — Wine and Beer 

On the Mouldering of Bodies. — Paper, Brown 
Coal, and Mineral Coal .... 

On Poisons, Contagions, and Miasms 



261 



266 
275 

285 

293 

299 
303 

325 

335 



APPENDIX. 

Growth of Plants without Mould 383 

On the Action of Charcoal on Vegetation . . . 386 

On the Rotation of Crops at Bingen, on the Rhine . 390 

On a mode of Manuring Vines 390 

On the Manuring of the Soil in Vineyards . . . 391 

Dr. Dana's Views respecting Geine ..... 394 

Analysis of Soils from Russia, &c. .... 409 

Berzelius on Animal Manure and Lime . . . 410 

Action of Ammonia ....... 411 

Root Secretions . . . . . . . .411 

Phosphate of Lime in Soils ..... 412 

Peat Compost 413 

Collection and Use of Manure in China . . . 415 

Addition to Note at Page 70 416 

Tables showing the Proportion between the Hessian and 

English Standard of Weights and Measures . 416 

Square Feet 418 

Cubic Feet 418 

Table of the Corresponding Degrees on the Scales of 

Fahrenheit, Reaumur, and Celsus, or Centigrade 419 

Index 421 



PREFACE 

TO THE AMERICAN EDITION. 



The interest excited in Great Britain on the 
appearance of this work by one of the most 
eminent chemists in Europe, and the high en- 
comiums bestowed upon it by individuals, and 
learned bodies, together with the various no- 
tices of it which have been published by Pro- 
fessor Lindley, Professor Daubeny, and others, 
all concurring in the opinion, that the informa- 
tion it contains is of great amount, and that 
from its publication might be dated a new era 
in the art of agriculture, induced the editor to 
suggest its republication in this country. 

As it was highly desirable to put the views 
of Professor Liebig to the test of actual experi- 
ment, arrangements were made for the cultiva- 
tion of a variety of plants upon the principles 
developed in the work. With his usual liber- 
ality and readiness in aiding the advancement 
of agriculture and horticulture, a gentleman in 
this vicinity, whose unrivalled conservatories 
and grounds afford the amplest facilities, per- 



Vm PREFACE TO THE AMERICAN EDITION. 

mitted a series of experiments to be instituted, 
upon many of his plants, trees, vines, and vege- 
tables. Other highly successful cultivators have 
also experiments in progress. The wish of the 
publisher to meet the frequent calls for the work 
at an early period, permitted, at this season of 
the year, only of such experiments as could be 
conducted under glass, which could not be ex- 
pected to furnish results of so much value as 
would have been the case had the publication 
been deferred to the autumn. The experi- 
ments, however, will be continued and varied 
during the summer, upon plants in the open 
air, and it is hoped, that more satisfactory re- 
sults will be arrived at. In the mean time, 
other cultivators, who may be induced to study 
the work, will have an opportunity of applying 
the principles on every variety of soil and agri- 
cultural product. With the hope of being able 
to embody, in this edition, the fruits of some 
of the experiments alluded to, its publication 
was for a time deferred. 

Although the experiments have not been in 
progress a sufficient length of time to allow in all 
cases of very decided inferences, in several instan- 
ces the growth and luxuriance of the plants have 
been highly satisfactory. The plant which was 
first treated was a seedling Norfolk Island pine 
(Araiicaria excelsa), a superb species of the 



PREFACE TO THE AMERICAN EDITION. IX 

larger coniferse. This plant was reared bj the 
editor in a pot, in which it has been growing 
three years, in the house. The growth each 
year has been from four to five inches, between 
October and April. In January last, it was 
supplied with charcoal-powder and ammonia? 
and watered with rain-water. Very soon it 
exhibited symptoms of increasing vigor, and has 
continued to flourish, having, at the expiration 
of thirteen weeks, increased in height rather 
more than six inches, with much new foliage, 
and several lateral shoots. 

The application of ammonia and charcoal to 
dwarf fruit-trees and grape-vines in pots, which 
was made more recently, has as yet produced 
no very obvious results. These would probably 
have been more evident, good or bad, had not 
an oversight of the gardener led to the neglect 
of an important step in the process, the direc- 
tions not having been distinctly understood. 

Experiments have been also made upon quick 
growing vegetables under glass ; boxes being 
so arranged, that the plants in every alternate 
box could be treated on Liebig's principles, 
while an equal number, containing plants of 
the same kind, were treated in the usual man- 
ner, and thus a comparison could be readily 
made. Of these, beans have exhibited the most 
apparent results. 



X PREFACE TO THE AMERTCAN EDITION. 

The application of the ammonia and charcoal 
to several green-house plants, has had most ef- 
fect, as jet, upon geraniums, and in the con- 
servatory in Boston, under the judicious and 
scientific direction of J. E. Teschemacher, Esq., 
the foliage has exhibited extraordinary devel- 
opement. We have yet to learn how far the 
flowers and fruit of the various plants under 
trial will be affected. 

The great object is to supply in moderate 
quantity, but constantly, ammonia, in what 
chemists term the nascent state, that is, as it 
is slowly evolved, from a salt containing ammo- 
nia, or produced, or as given off from charcoal 
which has absorbed it. This may be done by 
causing the slow decomposition of muriate of 
ammonia (sal ammoniac) by the aid of lime. 

Ammonia-water added in small quantity to 
rain-water may be given to the soil in which 
the plants are growing; or carbonate of ammo- 
nia dissolved in rain-water. 

Half an ounce of ammonia-water to a gallon 
of rain-water appears to be of sufficient strength; 
but in this we must be regulated by the nature 
of the plants to which it is to be given. In 
some cases the muriate of ammonia has been 
mixed with the charcoal, and the soil with air- 
slacked lime, the whole then mingled and placed 



PKEFACE TO THE AMERICAN EDITION. XI 

around the roots of the plant. In these cases, 
it is necessary to supply rain-water liberally to 
the soil. 

These are the outlines of the methods which 
have been thus far employed, and as yet no in- 
jurious effects have been observed, but on the 
contrary, the general appearance, and in some 
the growth and healthy aspect of the plants, 
have been remarkable. 

Although the fact that nitrogen is essential 
to the nutrition of plants was known before the 
publication of Professor Liebig's work, and it 
had, indeed, been ascertained by Saussure, that 
germinating seeds absorb nitrogen, it was not 
supposed that it is derived from the atmosphere 
exclusively. And this has been deemed the 
chief discovery of the author, so far as practical 
questions are concerned. It had been suspect- 
ed, that very small quantities of this gas in the 
atmosphere might furnish the nitrogen, ammo- 
nia being a compound of nitrogen and hydro- 
gen. It may be objected, that the quantity of 
ammonia present in the atmosphere, and in rain 
and snow water is exceedingly small, quite in- 
sufficient for the supply of all that enters into 
the vegetable structure. To this it has been 
replied by Professor Lindley, in an elaborate 
review of Liebig's work, that " the quantity of 
ammonia given off from thousands of millions 



XIV PREFACE TO THE AMERICAN EDITION. 

also the injurious action of weeds is explained, 
by their robbing the soil of that particular kind 
of food which is necessary to the crops among 
which they grow. Each will partake of the 
component parts of the soil, and in proportion 
to the vigor of their growth, that of the crop 
must decrease ; for what one receives the oth- 
ers are deprived of." 

"It is impossible for any one acquainted with 
gardening not to perceive the immense impor- 
tance of these considerations, which show, that 
by adopting the modern notion, that the action 
of soil is chiefly mechanical, the science of 
horticulture has been carried backwards, instead 
of being advanced ; and that the most careful 
examination of the chemical nature both of the 
soil in which a given plant grows, and of the 
plant itself, must be the foundation of all exact 
and economical methods of cultivation." 

In the English edition, this work is divided 
into two parts. The original intention of the 
publisher was to issue only that part which re- 
lates more particularly to agriculture. With 
this view, a few pages, viz. those in which vege- 
table mould and the decay of woody fibre are 
discussed, were transferred from the second to 
the first part. The publication of the entire 
work was decided upon after several pages had 
been printed, and the title of the first chapter 



PKEFACE TO THE AMERICAN EDITION. XV 

having been altered bj the omission of the word 
physiology, in conformity with the original plan, 
it was unavoidably allowed so to remain. 

This edition now comprises the entire work. 
A iew of the chemical illustrations have been 
transferred to the appendix, as less likely to 
interest readers in general, although of impor- 
tance to the chemist. 

The work has been divided into chapters, 
which will render it more convenient than the 
English edition. An introduction explanatory 
of chemical terms and of some of the theoreti- 
cal views of Liebig, has been prefixed, being a 
translation from a work of the same author. 
Many pages of notes explanatory of technical 
terms, &c., have been supplied ; these have not 
been distinguished by any mark, while those 
that are contained in the original work are 
marked L. or Trans. 

In the Appendix will be found many addi- 
tions, both theoretical and practical, comprising, 
it is believed, an impartial statement of the 
opinions and views of the distinguished Ameri- 
can chemists, who have with so much zeal and 
acuteness engaged in the investigation of the 
chemistry of agriculture. 

A copious index has been prepared and add- 
ed, in which the original work is deficient. A 
few grammatical errors in the original have 
been corrected. 



XVI PREFACE TO THE AMERICAN EDITION. 

The estimation in which this work was view- 
ed by the "British Association for the Advance- 
ment of Science," before whom it was brought 
as a Report, has been expressed by Professor 
Gregory, of King's College, in the remark, "that 
the Association had just reason to be proud of 
such a work, as originating in their recommen- 
dation." 

On the 30th of November, 1840, at the an- 
niversary meeting of the Royal Society, one of 
the Copley medals was awarded to the author ; 
and on this occasion, in his absence, the Presi- 
dent, the Marquis of Northampton, addressed 
his representative. Professor Daniell, as follows. 

" Professor Daniell, I hold in my hand, and 
deliver to you one of the Copley medals, which 
has been awarded by us to Professor Liebig. 
My principal difficulty, in the present exercise 
of this the most agreeable part of my official 
duty, is to know whether to consider M. Lie- 
big's inquiries as most important in a chemical 
or in a physiological light. However that may 
be, he has a double claim on the scientific world, 
enhanced by the practical and useful ends to 
which he has turned his discoveries." 

J. W. W. 

Cambridge, April 9th, 1841. 



TO 



THE BRITISH ASSOCIATION 



ADVANCEMENT OF SCIENCE. 



One of the most remarkable features of mod- 
ern times is the combination of large numbers 
of individuals representing the whole intelli- 
gence of nations, for the express purpose of 
advancing science by their united efforts, of 
learning its progress, and of communicating 
new discoveries. The formation of such asso- 
ciations is, in itself, an evidence that thej were 
needed. 

It is not every one who is called by his situ- 
ation in life to assist in extending the bounds 
of science ; but all mankind have a claim to 
the blessings and benefits which accrue from 
its earnest cultivation. The foundation of sci- 
entific institutions is an acknowledgment of 
these benefits, and this acknowledgment pro- 
ceeding from whole nations may be considered 
as the triumph of mind over empiricism. 

Innumerable are the aids afforded to the 
means of life, to manufactures and to commerce, 



XVIU PREFACE. 



by the truths which assiduous and active in- 
quirers have discovered and rendered capable 
of practical application. But it is not the mere 
practical utility of these truths which is of im- 
portance. Their influence upon mental culture 
is most beneficial ; and the new views acquired 
by the knovi^ledge of them enable the mind to 
recognise, in the phenomena of nature, proofs 
of an infinite wisdom, for the unfathomable pro- 
fundity of which, language has no expression. 

At one of the meetings of the chemical sec- 
tion of the " British Association for the Ad- 
vancement of Science," the honorable task of 
preparing a report upon the state of organic 
chemistry was imposed upon me. In the pres- 
ent work I present the Association with a part 
of this report. 

I have endeavoured to develope, in a manner 
correspondent to the present state of science, 
the fundamental principles of chemistry in gen- 
eral, and the laws of organic chemistry in par- 
ticular, in their applications to agriculture and 
physiology ; to the causes of fermentation, de- 
cay, and putrefaction ; to the vinous and ace- 
tous fermentations, and to nitrification. The 
conversion of woody fibre into wood and min- 
eral coal, the nature of poisons, contagions, and 
miasms, and the causes of their action on the 
living organism, have been elucidated in their 
chemical relations. 



PREFACE. 



I shall be happy if I succeed in attracting 
the attention of men of science to subjects 
which so well merit to engage their talents and 
energies. Perfect agriculture is the true foun- 
dation of all trade and industry, — it is the 
foundation of the riches of states. But a ra- 
tional system of agriculture cannot be formed 
without the application of scientific principles ; 
for such a system must be based on an exact 
acquaintance with the means of nutrition of 
vegetables, and with the influence of soils and 
action of manure upon them. This knowledge 
we must seek from chemistry, which teaches 
the mode of investigating the composition, and 
of studying the characters of the different sub- 
stances from which plants derive their nourish- 
ment. 

The chemical forces play a part in all the 
processes of the living animal organism ; and a 
number of transformations and changes in the 
living body are exclusively dependent on their 
influence. The diseases incident to the period 
of growth of man, contagion and contagious 
matters, have their analogues in many chemical 
processes. The investigation of the chemical 
connexion subsisting between those actions pro- 
ceeding in the living body, and the transforma- 
tions presented by chemical compounds, has 
also been a subject of my inquiries. A perfect 



XX PREFACE. 



exhaustion of this subject, so highly important 
to medicine, cannot be expected without the 
cooperation of physiologists. Hence I have 
merely brought forward the purely chemical part 
of the inquiry, and hope to attract attention to 
the subject. 

Since the time of the immortal author of the 
" Agricultural Chemistry," no chemist has oc- 
cupied himself in studying the applications of 
chemical principles to the growth of vegetables, 
and to organic processes. I have endeavoured 
to follow the path marked out by Sir Humphry 
Davy, who based his conclusions only on that 
which was capable of inquiry and proof. This 
is the path of true philosophical inquiry, which 
promises to lead us to truth, — the proper ob- 
ject of our research. 

In presenting this report to the British Asso- 
ciation, I feel myself bound to convey my sin- 
cere thanks to Dr. Lyon Playfair, of St. An- 
drews, for the active assistance which has been 
afforded me in its preparation by that intelligent 
young chemist during his residence in Giessen. 
I cannot suppress the wish, that he may suc- 
ceed in being as useful, by his profound and 
well-grounded knowledge of chemistry, as his 
talents promise. 

DR. JUSTUS LIEBIG. 
Giessen, September 1st, 1840. 



INTRODUCTION. 



FIRST ELEMENTS OF CHEMISTRY.* 



CHAPTER I. 

DEFINITIONS. 

1. The term Body is applied to all that, which occu- 
pies a certain space and possesses weight, that is, that 
which is attracted by the earth, 

2. In a more restricted sense, that which occupies 
space, is denominated Matter. In the most extended 
signification, matter is that which in any way becomes 
cognoscent to our senses. 

3. Bodies are found in three states, (a) solid, (b) flu- 
id, and (c) gaseous, or aeriform. 

(a). A body is denominated solid, when it possesses 
a particular form and its particles are difficultly or not 
movable among one another. 

(b). A fluid body is so named, when it takes the 
form of the vessel in which it is contained ; its particles 

* Selected and translated from Professor Liebig's new edition of 
Geiger's Pharmacy, published at Giessen. 
1 



2 INTRODUCTION. 

are easily movable among one another, and in a state of 
rest its surface is horizontal. 

(c). Gaseous bodies have no particular form ; their 
particles possess the property of repelling one another, 
and they perfectly fill the vessel in all directions which 
contains them. 

4. Extension. The space which a body occupies, 
according to its length, breadth, and depth, gives the 
idea of its figure. The bulk of a body is named its 
volume. 

5. The quantity of matter contained in a certain vol- 
ume is denominated its mass. 

6. The comparison of the mass of different bodies of 
the same volume, gives the notion of their density. We 
say that one body is denser than another, when in the 
same volume, the mass is greater in one than in the 
other. 

7. The phenomena which a body presents, while it 
acts upon our senses, are named the properties of the 
body. 

8. The cause which effects the changes in the material 
world, is named poxoer. 

9. Power effects either a change in the position or 
properties of a body. 

10. The influence which causes a body .or the par- 
ticles of the same to approach one anotheA is named 
attraction. 

11. Repulsion is defined to be that power which op- 
poses the power of attraction. 

12. Besides the power of attraction and repulsion 
certain matters have a decisive influence upon the changes 
in the properties of a body. These matters arc named 
imponderables. They are heat, light, electricity^ and 
magnetism. 



DEFINITIONS. GRAVITY. 3 

13. Three different powers of attraction are known, 
(a) gravity, (b) power of cohesion, and (c) chemical 
affinity. 

14. Gravity is distinguished from all other powers of 
attraction, in that, it acts at great distances. 

15. The force of this attraction stands in direct rela- 
tion to the mass of the body ; it increases inversely as 
the square of the distance. 

16. Since the mass of a body can be taken infinitely 
small in relation to the mass of the earth, it follows from 
(15), that every body, removed from the surface of the 
earth and left at liberty, must obey the attraction of the 
earth, and consequently fall. 

17. Two bodies on the surface of the earth show no 
observable inclination to approach one another, while the 
preponderating attractive power of the earth overcomes 
their particular mutual attraction. 

18. The force, with which one body presses upon 
another, depends upon the mutual attractive power of 
the earth and of the body ; it stands in proportion to the 
mass of the body. 

19. The greater or smaller mass of a body is meas- 
ured, by certain unities of mass called iceights. The 
instrument balance is employed to learn how much of the 
unities of mass are necessary in order to bring the mass 
of the body in equilibrium. 

20. The intensity of this counter-pressure, expressed 
in weights, is denominated the absolute weight of the 
body. Bodies of the same volume possess different ab- 
solute weights. The different weights of the body of 
the same volume are called specific iceights. 

" We say cork is a light, lead a heavy body, while we uncon- 
sciously compare their absolute weight with their volume, ^i^aen we 



4 INTRODUCTION. 

compare the weight of a volume of cork with a like volume of lead, 
we perceive the difference which exists with respect to the mass of 
both, tiiat is, their specific weight." * 

21. The power of cohesion is that power upon which 
depends the state (3) of a body. It acts between the 
smallest particles of homogeneous bodies. f 

22. The force which is necessary to separate the par- 
ticles of a body is in proportion to the intensity of the 
power of cohesion. 

" The cohesive power of solid bodies, for example metals, is de- 
termined by the weight which rods of a different metal are capable of 
bearing." 

23. In chemistry, the poicer of cohesion is that ten- 
dency which the parts of a body evince to become solid, 
or to maintain the state of solidity. The coherence of 
a body depends upon this inclination. 

24. The power of cohesion cannot be completely 
overcome by mechanical means. By grinding, pound- 
ing, &c., it is possible to change a great mass of sub- 
stance into many smaller masses, but the smallest piece of 
the pounded body is solid, that is, is coherent. 

25. The power of cohesion acts not at great distances, 
it is only evinced when the particles of a body are in 



* Or Specific Gravity ; for the methods of taking specific gravities, 
see Webster's Chemistry, 3d edit. p. 114. 

t Homogeneous bodies are those which are composed of particles 
of the same kind ; thus a mass of iron consists of particles of iron. 
Each particle, however, may be a componnd ; thus in marble each 
particle is a compound of lime and carbonic acid. When speaking 
of the mass we say it is made up of homogeneous particles, and they 
are held together by cohesion. 

The constituents, which we obtain by chemical analysis, are of 
different kinds, heterogeneous, and these are united by chemical at- 
traction or affinity. 



DEFINITIONS. ELASTICITY. 5 

immediate contact, or when the distance is so small as 
not to be perceptible. 

26. The limits of the power of cohesion between the 
particles of solid bodies are denominated hardness and 
softness. Ductile, tenacious bodies are so named, when 
their particles can be extended in different directions, 
through the employment of external force, and remain so 
extended when the external force is discontinued. Brit- 
tleness is the reverse of ductility. Elasticity is that 
property of the particles of a body which allows them, 
by pressure, to take another form, and, by the removal of 
the pressure, to assume their original state. 

27. In fluid bodies the power of cohesion is very 
slight, it is only necessary to employ a small force to 
separate their particles from one another. 

28. Gaseous bodies possess not the slightest cohesion, 
but their particles evince a tendency to repel one another ; 
they extend themselves on all sides when this extension 
is not prevented.* 

29. This inclination of the particles of gaseous bodies 
to repel one another is named the elasticity of gaseous 
bodies ; it can be measured by the pressure which their 
particles exercise on all sides. 

30. The elasticity of gaseous bodies decreases in pro- 
portion as their particles are separated from one another : 
it increases inversely in proportion as they approach one 
another. 

31. The power of cohesion acts upon many gaseous 
bodies, when they become condensed to a certain point, 
that is, when their particles are only separated from one 

* The term Gas is applied to all bodies when in the aeriform state. 
By air is understood our atmosphere which consists of different gases. 
1* 



6 INTRODUCTION. 

another by a small distance ; in this case they lose their 
gaseous form and become liquid.* 

32. Gaseous bodies cease to extend themselves when 
their elasticity is equal to the force, with which they are 
attracted to the earth. 

Gravitation acts upon the smallest particles of the gaseous bodies, 
and endeavours to draw them to the centre of the earth, and of course, 
to increase their density ; elasticity strives on the contrary, to remove 
their particles from one another. As this tendency ceases with the 
extension, there must exist a point where gravitation preponderates, 
and at this point they must obey the laws of fluid bodies, that is, they 
can no longer perfectly fill the vessel, in all directions, which contains 
them, and their particles in a state of rest must take a horizontal sur- 
face. — Faraday. 

33. In Chemistry, that tendency of a fluid or solid 
body, under certain circumstances, to take the gaseous 
form, is often denominated, the elasticity of the body. 

34. The faculty which a solid or liquid body possess- 
es, of taking, under ordinary conditions, a gaseous form, 
is named the volatility of this body. 

35. Solid or liquid bodies which have become gase- 
ous, are denominated vapors. 

36. The tendency which fluid or solid bodies possess 
of taking the gaseous form, and the pressure which their 
vapors exercise on all sides, is denominated the tension 
of these bodies. 

37. Jlffinity. — When we bring two heterogeneous 
bodies in contact with one another, they either lose their 
properties or remain unchanged. 

38. The reason why heterogeneous bodies change 



* The pressure required to render gases liquid varies with each ; 
thus carbonic acid requires a pressure of 540 lbs. at the temperature 
of 32°. Ammonia about 97 lbs. at 50°. Nitrous oxide (the exhilar- 
ating gas) 750 lbs. at 45°. See Webster's Cheviistry, p. 117. 



DEFINITIONS. AFFINITY. 7 

their properties by contact, proceeds from a peculiar 
power, different from the power of cohesion, and which 
we name the poioer of affinity (21, note). 

39. Chemical affinity acts between the smallest parti- 
cles of heterogeneous bodies : its action is only percep- 
tible when the bodies are in contact, that is, it acts at 
infinitely small distances. 

40. When the characters of two bodies become so 
changed through chemical affinity, that a third, a new 
body is formed, in the smallest particle of which, a 
certain quantity of the two bodies (that were brought in 
contact,) exists, the result is said to be a compound of 
these bodies. 

41. The new resulting body is named the product of 
the combination. (The expression, compound, is more 
generally given to the product of the combination of two 
bodies.) 

42. We say the body a possesses an affinity for the 
body 6, when it can form a compound with the body b. 

43. The bodies which exist in the compound, are 
named the constituents of the compound. 

44. When a solid unites with a fluid body, and the 
product of the combination is fluid, the result is said to 
be a solution. In a solution, the cohesive power of the 
solid body is destroyed by the chemical affinity of the 
fluid. 

45. When a solid is not dissolved by contact with a 
fluid body, they have either no affinity for one another, 
or the cohesive power of the solid body is greater than 
their reciprocal affinity. 

46. The evolution of light and heat generally takes 
place when a gaseous body unites with a solid or a fluid, 
— that is, it produces fire. This species of chemical 
combination is called a combustion. 



8 INTRODUCTION. 

47. When two gaseous bodies unite with one another, 
it follows, that their affinity is greater than their elasticity 
(39) : in most cases they lose their gaseous state, and 
become solid or liquid. Generally, gaseous bodies only 
unite with one another through the action of other powers 
or matters, by means of which, their elasticity is either 
diminished or destroyed. 

48. When a gaseous body unites with a solid or liquid 
body, it happens that either the former loses its gaseous 
state, and becomes in the new compound, solid or liquid; 
or it retains its state, and in this case, the solid or fluid 
body becomes gaseous. 

49. When a solid or liquid body by combining with a 
gaseous body, becomes itself gaseous, it follows, that its 
affinity for the gaseous body is greater than its power of 
cohesion. 

50. When a gaseous body by uniting with another 
body forms a solid or fluid compound, it follows, that its 
elasticity is smaller than their mutual chemical affinity. 

51 . The new properties which one body evinces when 
brought in contact with another body, are denominated 
the chemical properties of bodies. 

52. The affinity of one body for another is either sus- 
pended or diminished by every thing which prevents that 
near approach necessary to the action of the power of 
affinity. 

53. Heat. — The most ordinary observation shows, 
that a body can change its state without being brought in 
contact with another, or without this change depending 
upon chemical affinity. In all these cases, the change 
of state depends upon the quantity of heat present in the 
body. 



DEFINITIONS. HEAT. 9 

54. Under the name of heat, caloric* is considered 
an invisible, imponderable matter, which possesses the 
property of penetrating every substance, and of forming 
combinations with the same. 

55. Heat always tends to leave a body penetrated 
(heated) by this peculiar matter, (to become cold). A 
body, which possesses less heat (which is colder) than 
the surrounding bodies, always abstracts heat from those 
bodies (that is, it becomes warmer). 

56. That measure of heat which a body gives to or 
takes from the surrounding bodies, is named its tempera- 
ture. 

57. The loss of heat which a hot body sustains, in- 
creases with its temperature : that is, the hotter a body 
is m comparison with the surrounding ones, the more 
heat will it lose in the same time. 

58. In order to heat a body to a certain temperature, 
it is necessary to convey to this body a certain measure 
of heat, so that it can give to another body a determinate 
quantity of heat. 

59. We say that a body is icarm, when it gives out 
heat to our organs ; cold, when it abstracts heat. 

60. We observe as the most general action of heat, 
an increase of volume ; bodies extend themselves when 
they become heated. Gaseous, fluid, and solid bodies 
by the same increase of temperature undergo an unequal 
extension of volume. The extension of gaseous bodies 
is greatest ; and the extension of liquids greater than that 
of solids. 

* From the Latin, calor, heat. We have no evidence that caloric 
is material ; some consider heat as depending upon a tremor or vibra- 
tion excited in bodies. See Thomson on Heat and Electricity, 
2d edit. 



10 INTRODUCTION. 

Gl. The volume of a body, in most cases, increases 
or diminishes, according to its temperature. (The more 
that a body is heated, the greater is the increase in its 
volume ; when a hot body is allowed to cool, it assumes 
its original bulk, it contracts.)* 

62. This contraction and extension are emploj'ed in 
measuring the quantity of heat which a body has given 
out to, or taken from, the surrounding ones. The instru- 
ment employed for this purpose is named thermometer .\ 

63. An ordinary thermometer is a narrow tube, in one 
end of which a small ball is blown, and this is filled with 
a fluid ; generally with mercury. | When the mercury 
becomes heated in the ball, it extends ; and this exten- 
sion is visible by the rise of the column of mercury in 
the narrow tube. 

64. When a thermometer is plunged in melting ice, 
the mercury in the narrow tube stands at a certain point, 
which remains always the same, under the same circum- 
stances. At the level of the ocean, when placed in 
boiling water, the mercury expands, and stands at another 
point, which likewise never changes. 

65. The space between these two fixed points is di- 
vided into a certain number of equal parts, which are 
named degrees. The division is denominated the scale 
of the thermometer. Celsius divides this space into 100. 



* Advantage is taken of this in the arts, as in applying the tire to 
a wheel; the iron is heated, expanded, and applied, in cooling it con- 
tracts and binds the wood work firmly together. 

t From the Greek, signifying measurer of heat. These instru- 
ments are too often incorn^ct. Those made by I. S. F. Huddleston, 
185 Washington Street, Boston, may be recommended. 

i For a more particular description of thermometers, see Webster's 
Chemistry, p. 44. 



DEFINITIONS. THERMOMETER. 11 

Reaumur into 80. Fahrenheit into 180. The point 
Tiom which the division commences is named Zero.* 

66. A body heated to 30° or 40° Celsius, signifies 
that so much heat has been conveyed to it, that the mer- 
cury of the centigrade thermometer has been extended 
to this point, which, numbered from Zero, corresponds 
to the oOth or 40th division of the scale of the ther- 
mometer ; (86° or 104° F.) 

67. The thermometer shows by the expansion or con- 
traction of the mercury, when a body absorbs or gives 
out heat ; hence, it does not show the absolute quantity 
of heat which a body contains. 

68. Free, sensible, thermometrical heat is that quantity 
of heat which the mercury of the thermometer absorbs 
or gives out, in order to extend or contract itself to a 
certain point. 

69. The extension of a body by heat, proves that its 
particles are removed to a greater distance from one 
another ; it is (according to 22) clear, therefore, that the 
power of cohesion must become weakened. 

70. When solid bodies become heated to a certain 
point, their power of cohesion is so much weakened, 
that their coherence ceases, and they become Jluid. 
The point, at which solid bodies become fluid, is named 
their fusing point, 

71. When a fluid body is fully heated, the power of 
cohesion of its particles is completely destroyed, and it 
becomes gaseous. 

72. By the abstraction of the heat, these bodies again 
take their original state ; — the gaseous becomes a liquid, 
and the liquid a solid body. 

* The Zero in Celsius and Reaumur corresponds to 32" Fahrenheit. 



12 



INTRODUCTION. 



73. Vapors, in their restricted signification, are gaseous 
bodies, which, by the ordinary temperature and pressure, 
take again their original state. 

74. Gaseous bodies are denominated gases, when they 
preserve their state at the ordinary temperatures. 

75. In order to heat different bodies to the same 
temperature, it is necessary to have different quantities 
of heat. The unlike quantity of heat, which like weights 
of different bodies require, in order to possess the same 
temperature, is named the specific heat of a body. 

76. Through the union of certain conditions, whose 
connexion is denominated an experiment, generally by the 
mutual contact of bodies, with the application of heat, 
from a great number of substances, others can be ex- 
tracted of entirely different properties. 

77. A limited number of bodies, however, suffer no 
change when so examined. These are named simple 
bodies, — chemical elements. At present fifty-five such 
simple bodies are known, and, arranged alphabetically, 
are as follows : — 



Aluminum 


Cobalt 


Manganese 


Sodium 


Antimony 


Columbium 


Mercury 


Strontium 


Arsenic 


Copper 


Molybdenum 


Sulphur 


Azote 


Fluorine 


Nickel 


Tellurium 


Barium 


Glucinum 


Osmium 


Thorium 


Bismuth 


Gold 


Oxygen 


Tin 


Boron 


Hydrogen 


Palladium 


Titanium 


Bromine 


Iodine 


Phosphorus 


Tungsten 


Cadmium 


Iridium 


Platinum 


Uranium 


Calcium 


Iron 


Potassium 


Vanadium 


Carbon 


Latanium 


Rhodium 


Yttrium 


Cerium 


Lead 


Selenium 


Zinc 


Chlorine 


Lithium 


Silicon 


Zirconium 


Chromium 


Magnesium 


Silver 





78. A compound body is formed by the union of one. 



DEFINITIONS. METALS. 13 

two, three, or more, simple bodies ; the elements of a 
compound are also named the heterogeneoii-i parts of a 
body (21, note). A compound of one simple with 
another simple body is called a binary compound : a 
ternary contains three, and a quaternary four elements. 

79. Compounds are divided into three classes. All 
binary compounds belong to the first class. For exam- 
ple : — Sulphuric acid, potash, alumina ; when one 
binary unites with another binary compound, a binary 
compound of the second class is formed, — as, sulphate 
of potash. This class of compounds contains either 
three or four elements. By the combination of a com- 
pound of the second class, with another of the same 
class, a compound of the third class is formed, — as, 
alum, &c. The elements of the compounds in the 
second and third classes, are also called the ultimate con- 
stituents of the compound. 

80. Two great groups are formed by comparing the 
external characters of the elements. Those of one 
group possess a metallic lustre, — those of the other group 
not. The latter are sometimes named metalloids, the 
former metals. 

81. A combination of a body with oxygen, is called 
an oxide ; with chlorine, a chloride ; with sulphur, a 
sulphuret, he. 

82. The oxides of chlorine, bromine, iodine, sulphur, 
phosphorus, selenium, possess similar characters : they 
are soluble in water. Their solution has a sour taste, 
and changes the vegetable blues to red.* This class of 
combinations is named acids. 

* The blue liquor obtained by steeping purple cabbage leaves in 
hot water is a convenient test liquor for acids and alkalies. 

2 



14 INTRODUCTION. 

83. The chloride, bromide, and sulphuret of hych'O- 
gen, possess similar characters, and they are likewise de- 
nominated acids ; but in order to distinguish ihem from 
acids which contain oxygen, they are called hydrogen 
acids. 

84. Several metals, also, form acids with oxygen ; 
but the greater number of metallic oxides, are, in their 
relations, totally different from the acids. They form 
compounds which, for the most part, are insoluble in 
water ; those soluble in water have an alkaline taste, and 
possess the property of restoring the blue color of vege- 
tables, which have been reddened by acids. These also 
change many vegetable yellows to red or brown. This 
class is denominated bases^ and the soluble bases are 
named alkalies. 

85. The bases unite with acids, and the new com- 
pounds which result, are termed salts. 

86. The characters of the acids and bases, disappear 
in the salts in such a manner, that both, when united in 
certain relations, lose their property of changing the vege- 
table colors. This state is said to be neutral. 

87. Many salts redden vegetable blues, and others, 
again, restore the blue color of vegetables, reddened by 
acids : in the first instance, the salt possesses an acid, 
and in the latter an alkaline reaction. 

88. In general, that body is termed an acid, when it 
has the property of destroying alkaline characters, al- 
though only in one instance ; and it matters not whether 
it reddens vegetable blues or not. On the contrary, that 
body is termed a base, where it neutralizes the characters 
of any acid, while it unites with the acid. 

89. A simple body which is capable of forming either 
an acid or a base, is termed a radical ; a compound 



AFFINITY. CRTSTALLIZATION. 15 

radical consists of two or three simple bodies, and com- 
ports itself in a similar manner to the simple radicals ; 
that is, it is capable of forming acids and bases. 



CHAPTER II. 

AFFINITT. 

Division I. — Crystallization. 

90. When a fluid or gaseous body passes into the 
state of a solid, the particles of the fluid or gaseous body, 
possessing the greatest mobility, can follow, unrestrained, 
the power of cohesion. It is remarked, in this case, 
that the smallest particles of the body only attract them- 
selves in certain determinate directions ; there are formed 
regular, even-sided bodies, or crystals. The conversion 
of a fluid, or gaseous body, into the state of a solid, is 
termed crystallization. 

91. All bodies, which can become fluid or gaseous, 
without losing their chemical properties, can be crystal- 
lized. 

92. The regular forms which bodies take through 
crystallization, can all be derived from a very small num- 
ber of geometrical figures. The discussion of the con- 
nexion of all crystalline forms is the object of crystal- 
lography. 

93. When the conversion of a fluid body into the state 
of a solid is allowed to take place slowly and quietly, 
the crystals are in proportion larger and more regular. 
When the crystallization takes place rapidly, the crystals 



16 INTRODUCTION. 

are small ; very often so small that the particular form 
cannot be seen with the naked eye. 

94. A solid body can be converted into a liquid, by 
the application of heat (70), and by the chemical affinity 
of another (44). Heat^ and chemical affinity^ are the 
means by which bodies may be crystallized. It is a 
necessary condition, in their employment, that the chemi- 
cal properties of the bodies which are in contact do not 
change. 

95. When a fluid is brought in contact with a solid 
body, if they have an affinity for one another, the fluid 
will dissolve so much of the solid body as corresponds 
with their mutual affinity. Beyond this limit, when the 
circumstances are not changed, no further combination 
takes place ; in this instance the solution is said to be 
saturated. 

96. When heat, and the chemical affinity of a body, 
equally act upon a solid body, both endeavour to destroy 
the cohesive power of the latter ; and it generally 
happens, in this case, that the soluble power of the fluid 
increases with its temperature. 

" Many solids are more soluble in hot than in cold water." 

97. The term, saturated, thus depends upon the tem- 
perature of the fluid body ; a solution is said to be satu- 
rated by ordinary temperatures, by 40^, or by a low 
temperature. 

98. All bodies are not dissolved without a change in 
the composition, and it happens in many cases, that the 
solubility of a body is the same in both cold and hot 
flluids ; less often is the solubility smaller in a high tem- 
perature than in a lower. 

99. A saturated hot solution of a body, (whose solu- 



AFFINITY. CRYSTALLIZATION. 17 

tion is greater in a high temperature) by cooling allows 
that excess to precipitate, which the cold fluid could not 
retain, — Crystallization by cooling. In proportion to 
the difference of the solubility of a body at different 
temperatures, the crystallization through cooling is easier. 

100. Bodies which dissolve in cold and hot fluids, in 
the same quantity, can be obtained in the state of crys- 
tals, when by some means the dissolving fluid is re- 
moved, — Crystallization, by means of evaporation, — 
sloiv crystallization. The body can be crystallized, 
either by cooling or evaporation, according to the nature 
of the fluid employed in the solution. Common salt, 
for example, can be crystallized from water by evapora- 
tion, and from muriatic acid by cooling. 

101. Besides the employment of fluids, as alcohol, 
water, ether, mercury, &c., many bodies can be crys- 
tallized by melting, and then allowing the melted mass to 
cool. Regular crystals can be obtained in this manner, 
when only part of the melted mass is allowed to become 
solid, and then pouring off, at a certain temperature, what 
remains liquid.* 

102. There are bodies which crystallize equally well 
in both ways. Sometimes the crystalline form of the 
body is the same, after both methods, as common salt ; 
and in other cases the shape of the crystals are so differ- 
ent, that they cannot be derived from the same primary 
form, as, for example, sulphur. 

103. Bodies which crystallize in forms, incompatible 
with one another, are named heteromorphous. 

104. Many bodies, which possess a similar composi- 
tion, have the same crystalline form. It generally hap- 

* See Webster's Chemistry, paragraph 1139. 

2* 



18 INTRODUCTION. 

pens, in this case, that the crystalline form is dependent 
upon the composition and the similarity of the chemical 
properties of the constituents. 

105. Two or more bodies of the same class, which, 
when united with a third body, form a compound of the 
same crystalline form, are denominated Isomorphous. 

106. The external qualities of a body, form, transpa- 
rency, hardness, &c., depend upon a certain position of 
the particles of a body which is influenced by the power 
of cohesion. Hence, it follows, if the particles of a 
body are prevented taking that position in which they 
form a regular crystal, when thus the directions are 
changed in wdiich they are most powerfully attached to 
each other, that the external characters of the body, in- 
dependent of the chemical properties, will also be 
changed. 

107. Such solid bodies are called amorphous. 

" Sulphur heated to 1G0°, and quickly poured into cold water, does 
not crystallize ; it remains transparent, soft, and may be drawn out 
into long threads. Barley-sugar is amorphous sugar ; crystallized 
glass is opake, white and hard as flint ; the ordinary glass is amor- 
phous. Sulphuret of antimony is a black powder, but when thrown 
into water while red hot, it is of a red brown color. In many amor- 
phous substances, barley-sugar, amorphous sulphur, &c , a change of 
their characters takes place after some time ; perfectly transparent 
amorphous sulphur becomes opake and hard, barley-sugar loses 
its transparency, its fracture, which was conchoidal, appears then 
even, and shows internally crystallized forms. These observations 
prove the remarkable fact, that the smallest particles of a solid are, to 
a certain extent movable ; agreeing also with the fact, that they are 
not in perfect contact." 

108. When many crystalline bodies become heated, 
a remarkable appearance is observed, the crystal breaks 
in all directions with a certain force, and is changed into 
a more or less fine powder, — they decrepitate. This 



AFFINITY. — CRYSTALLIZATION. 19 

phenomenon is thus explained ; these crystals expand 
unequally in different directions, in one direction more 
than another ; while thus, the smallest particles follow 
in one direction, and not in the other, a separation of 
the two is the result of the action of heat. It is remark- 
ed sometimes with heteromorphous bodies, that the 
smallest particles, after the decrepitation, assume an- 
other form. 

109. When a fluid is saturated at a high temperature 
with a body, — for example, a salt, it still possesses the 
property of dissolving other bodies, for which it has an 
affinity. 

110. When a crystal is placed in a fluid, super- 
saturated with the same body, it begins to increase on 
every side. (This appearance proves that an attraction 
takes place between the crystal already formed, and 
those parts which are being formed. 

When we place in a saturated solution of two salts, a and b, a crys- 
tal of the body a, the excess of the dissolving body a crystallizes first; 
a similar effect is produced with the body h, when a crystal of b is 
placed in the solution ) 

111. When a saturated solution of two or more salts 
has deposited crystals by cooling, each crystal contains 
either an uncertain proportion of each of the dissolved 
bodies, or the crystals merely lie near one other, with- 
out being a mixture of the bodies which were dissolved. 

The sulphates of copper, iron, and zinc dissolved together in hot 
water, afford crystals which contain copper, iron, and zinc ; nitrate of 
potash and carbonate of soda crystallize out of the same solution, but 
merely lie near one another." 

112. The fluid, from which crystals have been de- 
posited, is denominated mother-ley as the mother-ley of 
common salt, &c. 



20 INTRODUCTION. 

113. Many crystals during their deposition, unite 
with a certain portion of the fluid, which in tliis case, 
becomes also solid. Crystals deposited from an aque- 
ous solution and containing water, are said to contain 
ivater of crystallization. In this case, it very often 
happens that the form is dependent upon the quantity of 
water of crystallization. 

114. Many bodies which contain water of crystalli- 
zation, lose either the whole or part of this water by 
evaporation at the ordinary temperature. They lose 
their regular form, become opake, or fall into a fine 
powder. — Effioresccnce. 

115. Many crystallized bodies, which contain this 
water, when heated to a certain point, suddenly change 
their form, and in this case, the change of the form de- 
pends upon a certain loss in their water of crystalliza- 
tion. 

116. Many salts containing water, melt by the appli- 
cation of heat, while they dissolve in their water of 
crystallization. In this case, the solid water has be- 
come liquid, and a part of the salt has dissolved in this 
liquid water, while the other portion has been deposited 
without water. 

117. Most salts containing water lose this water by 
the application of heat without melting, and lose at the 
same time their transparency and form. When again 
brought in contact with water, they form the compound 
containing water, become solid and cohering while a 
new crystallization takes place. 

118. When a body becomes quickly solidified in its 
solution, the particles of the surrounding fluid prevent 
the deposited body from forming large crystals, which 
appear then in the state of a fine powder. This species 



AFFINITY. CRYSTALLIZATION. 21 

of ciyscallization is called precipitation and the deposit- 
ed body a precipitate . 

Exp Into a wine glass of lime water drop some oxalic acid, Si pre- 
cipitate will subside, — oxalate of lime. 

119. When in a compound of a fluid with another 
body, the fluid becomes solid, its affinity for the dis- 
solved material ceases and a separation of the two fol- 
lows, (frozen wine, frozen vinegar, &c.) 

120. A fluid, which contains foreign substances, can 
only crystallize, when the cohesive power of its parti- 
cles is greater, than its affinity for those bodies with 
which it is in contact. 

121. When a solid is only partially deposited from a 
fluid, so that part remains dissolved, it follows, that the 
affinity of the fluid body is not great enough to over- 
come the cohesive power of the dissolved solid body. 
In this case, by the addition of more of the fluid, the 
whole can be retained in solution. 

122. When a solid body is so deposited from a fluid 
that nothing more remains in solution, they either have 
no affinity for one another, or the cohesive power of the 
particles of the solid body is greater than their affinity 
to the fluid. 

123. When a solution of a body A, is brought in 
contact with the solution of another body B, it gener- 
ally happens, that a new solid compound is deposited, 
which contains A and B. The new compound arises 
undoubtedly from the chemical affinity of the two bodies 
A and B for one another, but their separation from the 
fluid depends upon the predominating cohesive power 
of the particles of the new formed body, that is, upon 
their insolubility in this fluid. 



22 INTRODUCTION. 

124. Hence, it follows, that when the nature of the 
dissolving medium is changed, a body can be obtained 
in the solid state without cooling and without evapora- 
tion ; that is, it can be obtained crystallized when its 
affinity for the new dissolving fluid is less than its cohe- 
sive power. 



Division II. — Combination. 

125. The affinity of bodies is of different degrees. 

126. The property which bodies possess of uniting 
with one another, that is, their affinity is dependent 
upon, (a) their state of cohesion, and (6) the tempera- 
ture, in which both are brought in contact with one 
another. 

127. (a) Influence of the state of cohesion upon the 
combination of bodies. Two bodies can only unite 
with one another when the cohesive power of the par- 
ticles of one or of both, is smaller than their chemical 
affinity. 

128. When two bodies combine with one another, 
their particles must be easily movable, that is, they 
must be capable of changing their situation, or otherwise 
they cannot come in contact with each other. The first 
most general condition, necessary to the formation of 
a compound is, that the cohesion of one or boih of the 
bodies must be overcome. This is accomplished either 
by the melting or dissolving of one or both of the 
bodies. 

129. Two solid bodies of powerful affinity unite with 
one another only when in contact, when the product of 
the compound is solid, it follows that the particles of 



COMBINATION. INFLUENCE OF TEMPERATURE. 23 

the intermediate compound prevent the perfect union of 
the other imperfect combination (oxalic acid and lime). 

130. When in the moment of combination of two 
solid bodies, the new compound, or one of the constitu- 
ents, becomes liquid, the combination of solid bodies in 
these cases is perfect. As for example, salt and snow ; 
copper and sulphur finely pounded, quickly mixed to- 
gether become red hot, and sulphuret of copper results. 

131. Gaseous bodies whose elasticity in the ordinary 
state is greater than their affinity for solid or fluid 
bodies, only unite with the latter, when brought in con- 
tact with these in the moment of their separation from 
other fluid or solid bodies, thus immediately before 
taking the gaseous state ; status nasccns, nascent state 
(sulphurets and acids, &c.). 

132. (b) Injiuence of temperature upon the combina- 
tion of bodies. It is clear that, by the change of the 
state of a body by the action of heat, a great influence 
must be exerted upon the play of affinity, while the 
state of a body is changed, its cohesion is weakened in 
a much greater degree than its affinity, and consequently 
its action and its affinity are increased. In the combi- 
nation of two bodies, heat acts not only upon the state 
but also upon the affinity of both of the bodies. 

133. When the distance of the constituents of a 
compound, or the elasticity of one of the constituents, 
by the action of heat, becomes greater than the sphere 
of chemical affinity, the constituents will separate. 

134. Hence, it follows, that two bodies possessing 
an equal affinity for each other cannot unite at a tem- 
perature, where their elasticity, or the distance of their 
particles is greater than the sphere of their attraction. 

135. Increase of the degree of affinity. The affinity 



24 INTRODUCTION. 

of two bodies is in some cases increased by the contact 
of a tliird, which unites with neither and possesses no 
affinity for the new compound, as platina, hydrogen, 
and oxygen. (See "Webster's Chem. parag. 1287). 

136. In all cases the affinity of two bodies is increas- 
ed by the contact of a third, which possesses an affinity 
for the new resulting compound. Predisposing affinity. 

137. Intimacy of chemical combination. From the 
variation of the influence, which heat and the power of 
cohesion exert upon chemical affinity there cannot exist 
a general measure of the intensity of affinity, and for the 
intimacy of chemical combination. 

138. It is only in some cases that an approach can 
be made in measuring the intimacy of a compound of a 
body A, with others B, C, D, E, &c., through the dif- 
ferent temperatures which are necessary to destroy the 
compounds AB, AC, AD, &c. Carbonates of magne- 
sia, lime, barytes, &c. 

139. The strength with which a body a is united to 
another, b, depends not only upon the intensity of their 
affinity, but also upon the mass of one or other of the 
bodies. 

140. In a compound abb, a is more strongly attract- 
ed, than in the simple compound ab, when the mass of b 
is only half that in the former abb. 

141. Hence it follows, that in the compound abb, b 
is more weakly combined than in ab, because the mass 
of a in the latter is greater than in the former. 

142. When a body a is brought into contact with two 
bodies, b and c, which both possess an affinity for it, a 
is divided between b and c thus 

A 

B C 



DECOMPOSITION. 25 

The proportion of a, which is united with h and c, de- 
pends upon the degree of their affinity to c, and upon 
the quantity of b and c which are present. Let the 
affinity of h for a be as 5, that of c as 3, all other 
things equal ; a (= 8a) is divided between h and c in 
this proportion, 

A 



aaaaa 

B C 

143. When the quantity of c is enlarged, its affinity 
for a increases ; but this increase of affinity is not pro- 
portionate to the increase of quantity ; it is less. Let 
the quantity of c be doubled in the above example, and 
it will be found that 3 a are not abstracted from 6, but 
less. Say that its affinity is increased ^, it follows that 
h and cc equally divide a (=: 8a.) 

A 



aaaa aaaa 
B CC 



Division IIL — Decomposition. 

144. When a third body c, is brought in contact with 
a compound a6, the chemical characters in the com- 
pound are either changed or not. In the first instance, 
the result is said to be a decomposition of the compound 
ab. Decomposition is divided into (r?) total and (6) 
partial. 

145. The decomposition of the compound ab by c is 
said to be total, when the affinity of the body c to one 

3 



26 INTRODUCTION. 

of the constituents of the compound ah is such, that a 
new compound be is so formed, that all b is united with 
c, and the constituent a perfectly separated. 

AB 



A B 

aaaaaa bbbbbb 

cccccc 
C 



BC 



146. The total decomposition of a compound by 
means of the affinity of a third body very seldom takes 
place. 

147. When the decomposition of a compound takes 
place in a solution, the result is said to be a decomposi- 
tion by the moist way. Decomposition by the dry way 
occurs by the action of substances upon one another at 
a high temperature. 

148. The total decomposition of a compound de- 
pends generally upon the quantity^ and the state of the 
substances acted upon, the temperature and the nature 
of the fluid in which the decomposition takes place. In 
most cases, the decomposition is only partial, and be- 
comes total only under certain conditions. 

149. Laws which regulate the partial decomposition 
of a compound. — When a compound ab is brought in 
contact with another body, c, which possesses an affini- 
ty for 6, the two bodies a and c divide b between them, 
and two new compounds ab and be are formed. This 
division takes place in the way described in (143 and 
145). 

150. Let a =. Sa, h = Sb, c = 8f, and further, let 
affinity and quantity, (cohesion and temperature) be 
equal, it will be found that each of the new compounds 
contains the same proportion of b. 



DECOMPOSITION. — LAWS. 27 

B 



I aaaa 

AB < aaaa 

( hhbb 

A 



hbbh ) 

cccc > BC 

cccc ) 
C 



The one half of a (aaaa), is united with the half of 6 
(bbbb), and the remainder of a (aaaa) is disengaged and 
remains in the fluid : the same is the case with c, one 
half of which is likewise uncombined. 

151. The free portion of a (aaaa), and c {cccc) are 
not inactive in the mixture ; the free a (aaaa) constant- 
ly strives to decompose the compound be, and on the 
other hand, the free c (cccc) endeavours to unite with 
one of the elements of the compound ab. The decom- 
posing action of the two free bodies remains in equilib- 
rium, — that is, no further decomposition takes place. 

152. When the free cccc are taken away, the equilib- 
rium is destroyed ; the free aaaa share with 

] 7/77 of the compound < according to (142) 

and there will be found in the mixture, free aa and cc. 
B B 



bb bb bbbb bbbb 

aaaa cccc aaaaaaaa cccc 



AC AC 

153. When the free cc are being continually remov- 
ed, a new division takes place, till a total separation of 
the body c results. On the other hand, the same result 
takes place with the body a, when a part of the same is 
removed. 

154. By the addition of c to a compound ab, a portion 
of b is withdrawn, and a new compound be formed. If 



28 INTRODUCTION. 

the quantity of c be double, a further decomposition of 
the remaining ah is found to take place. 

155. In proportion as h is withdrawn from a com- 
pound aJ, the mass of a increases in proportion to the 
mass of 6, with which it remains combined ; conse- 
quently the affinity of a to 6 increases in the same pro- 
portion as the quantity of b diminishes. (139, 140.) 
Hence, it follows, that a compound nb can never be to- 
tally decomposed by the increase of the quantity of a 
third body c. 

156. These laws, as above explained, which regulate 
the decomposition of a compound, only take place when 
the state of the bodies acting upon one another and the 
state of the new resulting compound are the same. 
They undergo a great change when the ordinary state 
of one of the constituents of the compound, is different 
from the state of the other third body^ or from the state 
of the new compound. 

157. When a body c acts upon a compound a5, and 
the ordinary state of the body a is gaseous, a total de- 
composition of the compound ab results, with the per. 
feet separation of the body a (145). For example, 
carbonate of lime and sulphuric acid. 

158. The elasticity of the body a increases in this 
case the affinity of the body c, as in (153) when one of 
the elements is being continually removed out of action. 
When the body a is prevented taking the gaseous state, 
a partial decomposition only occurs. 

159. In (157) suppose the body a not to be gase- 
ous at the ordinary temperature, but to take this state at 
120° C, it will so happen that at the ordinary tempera- 
ture a partial decomposition only takes place, but at 
120'^ it will be total. For example, acetate of potash 



DECOMPOSITION. 29 

and sulphuric acid. Nitrate of potash and sulphuric 
acid. 

160. According as the quantity of the third body c 
is greater or smaller, the decomposition of the compound 
ah is more or less perfect. Hence it follows : when 
the. state and mass of the bodies acting upon one another 
can he changed by some temperatures .^ the decomposition 
is also changed, for it either takes place, or vice versa. 
As peroxide of iron heated to redness under a stream of 
hydrogen produces iron and water ; iron heated to red- 
ness in aqueous vapor, produces oxide of iron and hy- 
drogen. Carbonic oxide and peroxide of iron, afford 
iron and carbonic acid ; iron and carbonic acid afford 
carbonic oxide and oxide of iron. Sulphuret of anti- 
mony and hydrogen, give antimony and sulphuretted 
hydrogen ; sulphuretted hydrogen and antimony give 
sulphuret of antimony, and hydrogen ; potassium and 
peroxide of iron, iron and potash. 

161. The nature of the fluid in which the decomposi- 
tion takes place has an important influence on the result 
of the decomposition. A total decomposition occurs, 

I. When the body a of the compound ab is insoluble 
in the fluid, vjhile the compound be is soluble, as in 
(145 and 123). 

II. When the new compound be is insoluble and the 
body a soluble in the fluid, as in (123) as nitrate of 
baryta and sulphuric acid. 

162. (From 159 and 161,) it follows, that the result 
of the decomposition is changed according as it is ac- 
complished by the moist or dry way ; or according as 
the cohesive power or elasticity of one or the other 
bodies acts in preponderance. 

3* 



30 INTRODUCTION. 

For example, — boracic acid is perfectly separated from all its com- 
pounds by weak acids in the moist way; but in the dry way, it resists 
the strongest acids. In the moist way, sulphuric acid decomposes 
phosphate of lime, but in the dry way, phosphoric acid decomposes the 
sulphates, &c. 

163. It follows, further, That the result of the de- 
composition changes with the nature of the fluid (122). 

164. When two compounds, AB and DC, are 
brought in contact with one another, and their constitu- 
ents possess an opposite affinity for one another, a dou- 
ble decomposition takes place. 




165. When state and solubility are equal and the 
:affinity different, the decomposition is only partial ; and, 
in this case, the mixture will contain four compounds 
A B, AD, DC, and C B. A solution of sulphate of 
peroxide of iron, mixed with acetate of potash, is col- 
ored dark brown ; sulphate of lime, in contact with 
common salt, dissolves in a larger quantity than in 
water. 

166. When the state or solubility of the constituents 
of the compounds A B and D C are different, or the 
state and solubility of one or other of the new resulting 
compounds is also different, a partial or total separation 
of one, or of both, takes place. 

167. These decompositions are modified, or changed 
according to the temperature and the nature of the fluid, 
in which the decomposition takes place (158, 159, 160, 
161). 



DECOMPOSITION. 31 

" For example, nitrate of lime and carbonate of ammonia, at the 
ordinary, and at a high temperature." 

168. The decomposition of a compound, A B, by 
a third body, C, whose affinity for the constituent B, 
is less than that of A for B, can be assisted by means 
of a fourth body, D, which possesses an affinity for A. 
For example, alumina is not decomposed by means of 
carbon and chlorine taken separately, but acting to- 
gether, there result carbonic oxide and chloride of 
aluminium. 

169. Predisposing affinity (136) effects also a change 
upon the nature of the decomposition. 

170. Laws which regulate the decomposition of triple 
compomids, by heat and the predisposing affinity. When 
a compound, containing three or more elements, is de- 
composed at a great heat, the constituents unite in 
new relations, forming new compounds, which are not 
decomposed by the temperature in which they were 
formed. 

171. When a compound of three or more elements 
is exposed to a great heat, in contact with another com- 
pound, which possesses the property of forming with 
two of the elements of the former, a new compound, 
capable of resisting the action of heat, the remaining 
constituents will form one or more new gaseous combi- 
nations. 



32 INTRODUCTION. 

CHAPTER III. 

LAWS OF CHEMICAL PROPORTION. 

172. 1. Law deduced from Experiment. The 
quantity of A, which unites with B, in order to form 
the compound A B, is invariably the same, perfectly 
unchangeable. 

"Under all conditions, water contains 88.91 oxygen, and 11.09 
hydrogen ; or 100 oxygen, and 12.479 hydrogen ; or 1 oxygen, and 8 
hydrogen. Sulphuric acid contains 40.14 sulphur, and 59.86 oxygen ; 
or 201.17 sulphur, and 300 oxygen ; or 16 sulphur, and 24 oxygen." 

173. 2. Law deduced from Experiment. When a 
body, A, unites with another, B, in several propor- 
tions, the quantity of B, in the second degree of com- 
bination, is double that in the first, three times that in 
the third, four times greater in the fourth, &c. 



A-f B 


1st 


degree 


of combination 


B = l 


A + BB 


2d 


« 


(< 


B = 2 


A + BBB 


3d 


n 


a 


B = 3 


A + BBBB 


4th 


(I 


<( 


B = 4 


A + BBBBB 


5th 


a 


(( 


B = 5 



For example, the degrees of oxidation of azote, (nitro- 
gen,) sulphur, &c. 

Or the relation is as follows : — 



AA + BBB; A:B 

AA + BBBBB ; A : B 

AA 4- BBBBBBB ; A : B 



2: 3 
2:5 
2:7 



174. 3. Law deduced from Experiment. The quan- 
tities in which bodies unite among one another, are pro- 
portional. 

175. When a certain quantity of body, A, unites 



LAWS OF CHEMICAL PROPORTION. 33 

with 3 B, and 4C, and when B and C combine with 
another D, the quantities of B and C, which unite with 
D, are in the proportion of 3 to 4. 

176. If 3 lb A unites with 5 lb. B, and 5 lb. B 
with 2 lb. C, it will be found that 3 lb. A will most 
accurately combine with 2 lb. C : that is, when both 
can enter into combination with one another. 

A : B : : 3 : 5 
B : C : : 5 : 2 



A : C : : 3 : 2 

177. If the combining proportion of A, which unites 
with B and C, be known, it follows clearly that the 
combining portion of B, which unites with C, is also 
known. 

178. When 10 A, unite with 3 B, 6 C, 5 D, 7 E, 
&c., it will be found that 3 B, unite accurately with 

6 C, to 9 B C ; 6 C, with 5 D, to 1 1 C D ; 3 B, with 

7 E, to 10 B E, &c. : it, of course, being understood, 

that they possess an affinity for one another : 

A : B : : 10 : 3 
A : C : : 10 : 6 
A:D::10:5 
A : E : . 10 : 7 



B : C ; D : E : : 3 : 6 : 5 : 7 



179. Consequently, if the combining proportion of 
one body, for example, oxygen, which unites with all 
others, be known, the numbers which are found will 
express, — 

1. The combining proportion in which they unite 
with oxygen ; and, — 

2. The combining proportion in which they unite 
among one another ; it being, of course, understood 
that they possess an affinity for each other. 



34 INTRODUCTION. 

By this, and similar methods, the combining numbers 
of bodies have been obtained, of which tables will be 
found in modern chemical works. 

180. These numbers thus denote the weight of the 
different substances tchich enter into combination with each 
other ; they have received the name of chemical propor- 
tions. 

181. These numbers have also received the name of 
equivalents. 

" Therefore, in order to separate one of the constituents of a com- 
pound, as for example the potassium from the compound of this sub- 
stance with oxygen, by silver, sulphur, or hydrogen, &c., it is only ne- 
cessary to replace 1 equivalent of potassium by 1 equivalent of silver, or 
1 equivalent of sulphur, or hydrogen, &c. And on the other hand, to 
separate the oxygen in the same compound by sulphur, chlorine, 
iodine, bromine, »&c., all that is necessary is to have for every 100 
oxygen, 1 sulphur, 1 chlorine, 1 bromine, 1 iodine." 

182. Hence, the equivalent of a simple body is that 
combining proportion of the body lohich is necessary to 
unite with 1 sulphur, 1 chlorine, 1 silver, 1 potassium, 
^c, in order to form a compound. 

183. When a body unites with oxygen in more pro- 
portions than one, its true equivalent is doubtful. 

In order to remove this doubt, it has been agreed to con- 
sider that number the equivalent of the body, which unites 
with 100 oxygen in the loioest degree of oxidation. 

184. When one or more equivalents of a simple body 
A, unite in more proportions than one with another body 
B ; the quantities of B will be found to be multiples of 
the equivalent of B expressed in whole numbers. 

185. The number of the equivalent of a compound 
body is the sum of the numbers of the equivalents of its 
constituents. 

186. When one compound body unites with another, 



LAWS OF CHEMICAL PROPORTION, 35 

it is always in that combining proportion whicli expresses 
the numbers of their equivalents. 

187. The doctrine of proportion thus enables us to 
designate more distinctly the most important classes of 
certain chemical compounds, already noticed. 

188. We understand under the term oxygen acids^ 
compounds of metalloids with oxygen, in which one or 
two equivalents of the radical are united with two or 
more equivalents of oxygen. The higher degrees of 
oxidation of many of the metals are also acids. 

189. Oxygen bases are, without exception, compounds 
of metals with oxygen ; many of which unite with oxy- 
gen in more proportions than one, and others merely 
have one degree of oxidation ; it has been agreed to 
consider the lowest degree of oxidation as a compound 
of one equivalent oxygen and one equivalent metal, cop- 
per and mercury, &c., excepted, 

190. JSCeutral salts are compounds of one equivalent 
acid and one equivalent base. 

191. With those acids, the equivalent of whose radi- 
cal is doubtful, that quantity is taken as the equivalent 
which is contained in an equivalent of their oxygen acid. 

192. By the term equivalent of an acid, is under- 
stood that quantity of the acid which possesses the prop- 
erty of neutralizing one equivalent of any base, which 
contains 100, that is, one equivalent of oxygen. 

193. The equivalent of a base is that quantity which 
unites with an equivalent of any acid, in order to form a 
neutral salt. 

194. As the equivalent of a compound body is the 
sum of the equivalents of its elements, it is easy, when 
the number is known, to calculate the number of the 
equivalents of each of the constituents, from the known 
composition of the body. 



36 INTRODUCTION. 

195. When the sum of the number of the equivalents 
of the constituents of a compound, that is, the equivalent 
of a compound, is unknown ; the number of the equiva- 
lents of the constituents is doubtful. Their relation, 
however, can be found, if the quantity of the constituents 
which has been determined by analysis in a certain weight 
be divided by the equivalent of the constituents. 

196. In all cases, the new products contain the sum 
of the equivalents of the elements out of which they 
have been formed, and this relation can always be ex- 
pressed in equivalents. 



CHAPTER IV. 

THEORY OF CHEMICAL PROPORTIONS. 

197. The laws according to which bodies combine, 
have been deduced from an accurate comparison of the 
composition of the compounds, and the phenomena 
which they present when mutually decomposed. These 
laws are expressions for facts, whose unchangableness 
and truth are opposed by no kind of experience. Chemi- 
cal proportions are independent of every theory, and 
stand in no relation to any hypothesis. 

The object of the science is not merely to confirm 
the truth of chemical proportions, but to search and in- 
vestigate the causes of their regularity and constancy. 

It is clear, that these causes stand in the most intimate 
relation with the physical constitution of the bodies, but 
sense and experience desert us when we attempt to 
fathom the ultimate causes of these phenomena. As 



THEORY OF CHEMICAL PROPORTIONS. 37 

these ultimate causes are not appreciable by our senses, 
ihey are consequently unknown, and for the most part 
inscrutable. Hence, at this point, experimental philoso- 
phy ceases and abandons the explanation to the imagina- 
tion. If a law of nature, with all its consequences, or 
a series of phenomena explained consecutively be op- 
posed by no experience, no fact, the connexion of the 
explanation with the phenomena is called a theory. The 
naturalist infers from the laws of nature, from the phe- 
nomena, their causes, and by a series of syllogisms he is 
led to an explanation of the phenomena, or in other 
words, to a theory. When two theories proceed from 
different or opposite conceptions of the facts of the phe- 
nomena, and both explain all facts and phenomena, it is 
doubtful which to adopt. When a series of phenomena 
are explained by only one theory, and when no single 
fact or experience opposes the same, there is every 
reason to believe, that this theory is the expression of 
the true cause of the phenomena. 

Hence, it follows, that the existence of such a reason 
cannot be denied, because the eyes cannot perceive and 
the hands cannot grasp it. No human eye has seen sound 
or the waves of light, yet their existence depends on 
syllogisms, demonstrated by numberless analogies. 

It is less to be denied, because it is impossible to un- 
derstand, how and in what manner the senses act. How, 
and in what way light produces warmth ; /lOJt;, and in 
what way heat boils water ; /iot<;, and in what gravity acts 
at such distances ; hoio the affinity of two bodies mutu- 
ally destroys the characters of both ; all is unknown. 

198. A view of the physical constitution of bodies, 
first propounded by Dalton, agrees so perfectly with all the 
phenomena, which composition and decomposition pre- 
4 



38 INTRODUCTION. 

sent, and such numberless analogies prove the same, that 
at present it must be regarded as the true expression of 
the reasons of chemical proportions. 

Atomic Theory. 

199. According to this view, matter is not infinitely 
divisible, but there exists a limit beyond which the par- 
ticles of a body cannot be further divided. These 
smallest indivisible portions of matter are denominated 
atoms ; and it is further believed, that the atoms are un- 
equally heavy. A body A consists of a number of in- 
finitely small imperceptible particles A, and a body B of 
a certain number of atoms B. 

200. When a body A possesses an affinity for a body 
B, the combination takes place so that the smallest par- 
ticle (atom) of A unites with the smallest particle (atom) 
of B. 

When one body unites with another in more propor- 
tions than one, the smallest particle of A combines with 
2, 3, or 4, &c., of the smallest particles of B. If it 
were possible to know the number of the atoms of a 
body, or to weigh the smallest particles, nothing could 
be easier than to determine the weight of a compound 
atom, but a single atom is infinitely small and not appre- 
ciable by the senses. 

We know, however, that A and B, for example, unite 
together by weight, in the proportion of 3 : 5. It is 
clear, therefore, in the supposition, that the compound 
A B, contained a certain number of the atoms of A, 
and the same number of the atoms of B, that the relation 
3 : 5 must express the due relative weight of the atoms 
A and B. The compound A B contains 100 atoms of 
A, and 100 atoms of B : the quantity of A weighs 5 



ATOMIC THEORY. 39 

grains, the quantity of B, weighs 3 grains ; hence, 1 
atom of A (100 atoms of A weigh 5 grains, how much 
1 atom) := yf gf^'n? ^^d one atom B yl^. Let the 
number of atoms of A and B, in the compound be 
equally great, but unknown, the relation by weight of 
5 : 3 never changes ; it matters not, how great or how 
small, the number of the atoms may be, if the atom of 
A weighs 5, the atom of B must weigh 3. The weight 
of 3 of the atom of B infers the weight 5 of the atom 
of A, and vice versa. These numbers, then, do not 
express the absolute, but the relative weight, merely of 
the atoms. 

1000 oxygen unite with 128 hydrogen, to form 1125 
water ; this relation by weight is as 1 : 8. If, now, 
water consists of the same number of atoms of oxygen 
and hydrogen, the weight of the atom of hydrogen will, 
in all cases, be 8 times smaller than the weight of an 
atom of oxygen. 

201. The reason why bodies only unite together in 
certain weights, in order to form compounds, that unlike 
weights of the same mutually replace one another, that 
bodies do not unite in all proportions, is thus explained 
by the view, that matter exists in the form of particles, 
not further divisible, but whose weights are different. 
There is no other supposition, which offers a more prob- 
able explanation, than the present. 

202. (1.) Gaseous bodies unite with one another, 
so that 1 volume of the one gas is combined with 1 vol- 
ume, 2 volumes, or 3 volumes, &c., of the other gas. 

(2.) The volume of the compound stands in a simple 
relation to the volume of the constituents. 1 volume 
oxygen, with 2 volumes hydrogen =i 3 volumes togeth- 
er, and produce 2 volumes of aqueous vapor. 



40 INTRODUCTION. 

1 vol. oxyg. with 2 vol. az. = 3 vol. produce 2 vol. protox. of az. 
1 " az. " 3 " hy. = 2 vol. " 2 " ammon. gas. 

1 " sulph. " 6 " hy. = 7 vol. «' 6 " sulphd. hydro. 

1 " chlor. " 1 " hy. =^ 2 vol. " 2 " muriatic acid. 

(3.) When one gas unites with another, in more pro- 
portions than one, the volumes of this gas stand in the 
same simple relation to one another, as the weights of 
the atoms. 

2 vol. azote, unite with 1 vol. oxygen, to protoxide of azote. 
2 " " " 2 " " deutoxide of azote. 

2 " '' " 3 " " hyponitrous acid. 

2 " " " 4 " " nitrous acid. 

2 " " " 5 " " nitric acid. 

We observe, that, by the combination of two gases, 
in all cases, the volume of the compound is either the 
same as the volume of the constituents, or a condensa- 
tion takes place. Hence, it follows, — 

203. *^ volume of a compound contains either one 
volume of each of its constituents^ or a multiple, or sub- 
multiple of one or more of the constituents. 

204. It is evident, that the laws of the combining 
proportion of gaseous bodies can be derived from the 
volume in which they unite, with even as much accura- 
cy, as by means of the balance. In this point of view, 
the knowledge of the specific weights of simple and 
compound bodies, in the gaseous state, is one of the 
most important means, to submit to the sharpest proof, 
the constitution of compounds obtained by other meth- 
ods. 



ATOMIC WEIGHT AND VOLUME. 41 



CHAPTER V. 

CONNEXION BETWEEN THE ATOMIC WEIGHT AND 
VOLUME OF A BODY. 

205. It has been already remarked, that the com- 
pression of solid and fluid bodies, their elasticity, and 
Other characters, have given rise to the opinion, that 
their smallest particles, the atoms, are not in perfect 
contact, but at certain distances from one another. 
This distance increases when the body is heated ; it be- 
comes smaller when the atoms are exposed to a certain 
pressure. Solid and fluid bodies expand unequally 
when heated, and the diminution of the volume by equal 
pressure is also very different. From these facts, it 
has been concluded, that the distances of the atoms of 
solid and liquid bodies is not the same in all. This 
inequality is not noticed in gaseous bodies ; all gases 
expand equally, for the same degree of heat, and their 
volume increases or diminishes equally for the same 
pressure. From these facts, the conclusion has been 
drawn, that the constitution, of gases is perfectly the 
same ; that the atoms of gases are, in all, equally distant 
from one another. Hence, it evidently follows, that 
tivo gases of the same volume contain the same number 
of atoms. When this proposition is regarded as true, 
the numbers which express the equivalent of hydrogen, 
azote, and some other bodies, are not the relative weights 
of the atoms of the same. 

2 volumes hydrogen unite with 1 volume oxygen. 

Hydrogen. Oxygen. 



42 INTRODUCTION. 

206. It is clear, when the gases of the same volume 
contain the same number of atoms, that 2 or 3 volumes 
of a gas must contain 2 or 3 times more atoms of the 
same. In water, 100 oxygen combine exactly with 
12.479 hydrogen ; the volume of hydrogen, as gas, 
amounts exactly to twice the volume of oxygen, whence 
it follows, that 12.479 hydrogen express the weight of 
2 atoms of hydrogen, and 1 atom thus will weigh J-^^-i^ 
= 62.395. 

207. The specific weights of the gases are their rela- 
tive weights by equal volume ; whence it follows, if the 
above proposition be regarded as true, that the true 
atomic weights of bodies must be proportional to their 
specific weights when in the state of gases. 

The theory of volumes presents some conveniences 
in judging of the composition of those compounds which 
are gaseous, or which can take the gaseous state. The 
specific weight of the same is the sum of the specific 
weights of the constituents in one volume, and the rela- 
tion of the volumes of the constituents accurately ex- 
presses the relative number of the atoms in the com- 
,pound. 



CHAPTER VI. 

ISOMORPHISM, OR THE CONNEXION BETWEEN THE EX- 
TERNAL FORM AND THE CHEMICAL COMPOSITION OF 
BODIES. CATALYTISM. 

208. In many chemical compounds one constituent 
can be partially or wholly taken away, and replaced par- 
tially or completely by another body, while the external 



ISOMORPHISM. 43 

form and its proportion of water (if it contains water of 
crystallization) remain unchanged. 

209. Those bodies or compounds which possess the 
property of mutually replacing one another in combina- 
tions, without changing the/orm of the same, are called 
isomorphous substances (from I'aog, like, and ^oQcp^, form). 

All the constituents of compounds are not isomor- 
phous, when the compounds possess the same form 
(arsenious acid and alum possess the same form, but the 
constitution is quite different) ; and all compounds simi- 
larly constituted do not possess the same form, (the form 
of the chlorate is different from that of the nitrate of 
potash). 

210. When we endeavour to form a clear conception 
of the reasons, that two bodies possess the same form, 
that the same two bodies form combinations of similar 
constitution, and these compounds also possess similar 
forms, there remains no other way but to seek these 
reasons, in the similar form of their smallest particles, 
and in the similar positions which they take in their com- 
binations. This leads most naturally to the existence 
of atoms and may be employed as a proof that the atom- 
ic theory is something more than a mere conception 
formed, in order to explain a series of phenomena. 

211. We regard in this work, the connexion of the 
external form with the chemical constitution as the 
surest guide to instruct us respecting the chemical con- 
stitution of compounds. 

212. Tivo elements of similar form produce coynbina- 
tions of similar form, when these contain a like number 
of atoms arranged in the same way. 

213. A compound which is isomorphous with one or 



44 INTRODUCTION. 

more others, possesses a similar composition and contains 
a like number of atoms of the constituents. 

214. We employ the atomic numbers, in order to 
express the composition of bodies, in a short, easy, and 
intelligible manner. It would be impossible to retain, 
in the memory, the numbers which express the compo- 
sition of compounds in two parts. The simple relation 
in which bodies unite, according to their atomic weights, 
is remembered with the greatest ease.* 



Catalytism. 



215. The decomposition of chemical compounds 
generally takes place by the action of other bodies, in 
such a manner, that the acting body forms a new com- 
pound, by uniting with one of the constituents of the de- 
composed body. 

216. The observation, that a certain class of com- 
pounds decompose themselves into new combinations, 
merely by contact with one another, without the acting 
body uniting with one of the new products, or without 
losing one of its constituents, has caused Berzelius to 
consider the above decomposition as dependent upon a 
new force, which new force is only called into action by 
the contact of the bodies, and the decomposition of the 
compounds is the result. He names it the catalytic 
force, and compares it with the peculiar activity of the 
human organization, which possesses the property of 

* For the explanation of chemical formulae, &c., see Webster's 
Chemislnj, 3d edit. 



CATALYTISM. 45 

preparing those substances from the food, which are 
necessary to its existence, as blood, &ic. 

Sugar and water in contact with yest are decomposed 
into carbonic acid and alcohol : amygdalin, in contact 
with emulsin, is decomposed into prussic acid and oil of 
bitter almonds : deutoxide of hydrogen, in contact with 
peroxide of manganese, is decomposed into oxygen gas 
and water : boiling thick syrup of sugar becomes, by 
the addition of ,00 po of oxalic acid, as fluid as water, 
and loses its faculty of crystallization. 

Although it cannot be denied, that these facts are in- 
explicable, according to the ordinary decomposition of 
a salt by means of an acid, yet it affords not the slight- 
est ground for the creation of a force by means of a new 
word, which likewise furnishes no explanation of the 
phenomena. The adoption of this new force is preju- 
dicial to the unfolding of the science, while the under- 
standing is satisfied with this plausible explanation, and 
thus places a limit to further research. 

The smallest quantity of the acting body (yest) which 
is sufficient to decompose a great mass of a chemical 
compound, can afford no ground to seek its explanation 
in a particular force (a small quantity of nitric acid gas 
is sufficient to form a great mass of sulphuric acid), and 
so long as it remains unknown what the yest loses in fer- 
mentation, so long must the explanation of this decom- 
position be left to future researches. 



46 INTRODUCTION. 



CHAPTER VII. 

THEORY OF THE CONSTITUTION OF SALTS. 

217. Under the term Salt, in the most restricted 
sense, is understood, a combination of two compound 
bodies, which both possess as a constituent, a common 
element, namely, a metalloid. 

The most important classes of salts are the follow- 
ing : — 

218. Oxygen Salts. — They are formed by the com- 
bination of a metallic oxide (of a base) with the oxide 
of a metalloid (acid) ; or, by the higher degree of ox- 
idation of a metal with another metallic oxide. That 
oxide is called a basic metallic oxide, which, in all cases, 
acts the part of a salifiable base. 

219. The capacity of a base to neutralize an acid, is 
independent of the quantity of its radical ; it is depen- 
dent upon the proportion of oxygen which it contains. 
(Consequences of 192, 193, and 202.) 

220. When a certain quantity of an acid is neutral- 
ized by different bases, the quantity of the oxygeu in all 
these bases is the same, however different their weight 
may be. (Consequences of 192-202.) 

221. The proportion of oxygen of the acid stands in 
a simple relation to the oxygen of the base, which forms 
with it a neutral- salt. The proportion of oxygen of 
both is either the same, or a multiple in whole numbers 
of the oxygen of the base. 

(Consequences of 202. The oxygen of the base must 



THEORY OF SALTS. 47 

be related to the oxygen of the acid, as the number of 
the atoms of the oxygen of the base is to the number of 
the atoms of the oxygen of the acid.) 

222. The saturating capacity of an acid is the con- 
stant quantity of oxygen in different quantities, by 
weight, of bases, which is necessary in order to form a 
neutral salt with 100 parts of acid ; 100 parts of ni- 
tric acid saturate a certain quantity of any base con- 
taining 14.75 oxygen, consequently, the saturating ca- 
pacity of nitric acid is 14.75, or -^th of its oxygen. 

The saturating capacity of. sulphuric acid is 19.96. 
Hence, the saturating capacity of sulphuric acid (19.96) 
is said to be greater than that of nitric acid (14.75), and 
we express thereby, that with the same quantity of 
acids, a greater quantity of base is neutralized by the 
one than by the other. (Consequences of unlike atom- 
ic weights of the acids.) 

223. The composition of a metallic oxide can be 
found, from the composition of its neutral compounds 
with one or two acids, when the saturating capacity of 
the acid is known. 

224. Those combinations of an acid with different 
bases in which the saturating capacity of the acid is con- 
stant, are denominated the neutral salts of this acid, 
whatever may be the reactions of the salts. 

225. Those salts are named basic^ which contain 
twice, thrice, &c., the quantity of base of the neutral 
salt. 

In the basic salts of sulphuric acid, the oxygen of 
the base is to that of the acid as 2 : 3, or 3 : 3, &c. 
They consist of 2 or 3 atoms base, with 1 atom acid. 

226. Double Salts are compounds of two or more 



48 INTRODUCTION. 

salts of different bases, or acids. There exist neutral 
and basic double salts. 

227. Compounds of acids with water, in which the 
quantity of the oxygen of the water is the same as the 
oxygen of a metallic oxide which forms with these acids, 
neutral salts, are called the hydrates of these acids. 
(They are salts, in which, the basic metallic oxide is re- 
placed by an atom of water.) 

228. The basic water in the hydrated acids can only 
be separated by means of a powerful base. 

229. Acid Salts are combinations of the neutral salts 
with the hydrate of the same acid. (Bisulphate of pot- 
ash, for example, a double salt of two bases, in which 
the water is one. Exception, — bi-chromate of pot- 
ash.) 

230. A class of salts, in which the hydrate water of 
the acids enters into the composition of the salts, is 
named Halhydrate.* 

Neutral sulphate of soda contains 10 atoms water, 
which can be perfectly separated by 100^ C. ; the hy- 
drate water of the acid is perfectly replaced, and separ- 
ated by its combination with soda ; the 10 atoms of water 
which the salt contains is water of crystallization. Sul- 
phate of zinc contains 7 atoms of water, of which 6 
atoms can be separated by 100'^ C. ; the 7th atom is 
more powerfully united. 

231. Halhydrates do not unite with one another. 
This class of salts forms no double salts with one an- 
other. 



* Being at a loss for a word to distinguish this class of salts, I have 
adopted the expression of the original, which is derived from the 
Greek word aks, salt. — L. 



HALHYDRATES. ,49 

232. Halhydrates only form double salts with those 
salts in which the acid has lost its hydrate water. (Sul- 
phate of zinc, sulphate of lime are halhydrates, and do 
not unite with one another. Sulphate of zinc, however, 
as well as sulphate of lime form double salts with the 
sulphates of potash and soda.) 

233. In the double salts, the hydrate water of the hal- 
hydrates is replaced by a corresponding quantity of an- 
other salt. 

The knowledge of the halhydrates, that is, of those 
salts, which do not possess the property of forming 
double salts with one another, is, in many decomposi- 
tions, of the greatest importance. If it is wished to 
change acetate of lime into acetate of soda by double 
decomposition with sulphate of soda, according to cal- 
culation for 1 eq. acetate of lime, it is only necessary to 
have 1 eq. sulphate of soda ; but it is requisite to have 
double the quantity of the latter, as the gypsum is a hal- 
hydrate, with water of crystallization. By contact with 
the sulphate of soda, the halhydrate water is replaced by 
1 atom of sulphate of soda, and there is produced a 
double salt, which is precipitated in the water. The 
hardening of hydrated gypsum, when it is in the state of 
powder, moistened with many saline solutions, arises 
from the same cause. 

234. When, in a neutral salt, the quantity of the met- 
al is increased or diminished, the salt remains neutral, 
(consequence of 220) for the saturating capacity of the 
acid is not changed. 

235. If in a neutral salt, the oxygen of the base is 
increased, the saturating capacity of the acid, and there- 
fore their quantities must be increased in the same rela- 
tion, when the salt should remain neutral. In the oppo- 

5 



50 INTRODUCTION. 

site case, the salt will be either totally or partially con- 
verted into a basic salt (consequences of 220 and 221). 

236. Certain compounds of two metallic sulphurets, 
in which the proportion of sulphur of one of the metallic 
sulphurets corresponds to the proportion of oxygen of a 
basic metallic oxide and the proportion of sulphur of the 
other sulphuret corresponds to the proportion of oxygen, 
of an oxygen acid of the same metal, are denominated 
sulphur salts. 

Chlorine salts are compounds of one, two, three, or 
more metallic chlorides ; fluorine salts are compounds 
of two, &c., metallic fluorides, &ic. 

237. When an hydrogen acid is brought in contact 
with metallic oxides, both are mutually decomposed ; 
there results water from the hydrogen of the hydrogen 
acid uniting with the oxygen of the metallic oxide, and 
the radical of the hydrogen acid unites with the metal of 
the metallic oxide. (Exception, — with alumina, &c.) 

238. The basic metallic oxides are divided into cer- 
tain groups, in reference to their solubility in water, and 
their capacity perfectly to destroy the acid characters of 
the acids. A knowledge of the same will be found of 
great use. 

a. Pure alkalies are the oxides of potassium, so- 
dium, lithium ; they are very soluble in water, the solu- 
tion attacks the skin, and they form soluble salts with 
carbonic acid.* 

b. Earthy alkalies are the oxides of barium, stron- 
tium, calcium, magnesium ; they are difficultly soluble 
in water, not so caustic, and form with carbonic acid, 
insoluble salts. 



* Ammonia, whicli is composed of hydrogen and nitrogen, is often 
called the volatile alkali j it is a gas. 



ALKALINE EARTHS. 51 

c. Earths, they are totally insoluble in water, have no 
action upon vegetable colors, and do not unite with car- 
bonic acid. To this group belongs alumina, &c. 

The salts of the alkalies (a b) were formerly named 
neutral salts, and those of the earths and other metallic 
oxides intermediate. 

239. The four simple bodies, viz. chlorine, bromine, 
iodine, fluorine, before mentioned, are called haloid.* 

240. The combinations of the haloids with metals are 
named haloid salts.f 



* From aX;, sea salt, and iTSes,form, for being analogous to sea- 
salt. 

t For a more particular description of the salts, see Webster's Chem- 
istry, 3d edit. 104. 



\ 



ORGANIC CHEMISTRY 



APPLIED TO 



AGRICULTURE, 



CHAPTER I. 

OF THE CHEMICAL PROCESSES IN THE NUTRITION OF 
VEGETABLES, AND THE CONSTITUENT ELEMENTS 
OF PLANTS. 

The object of organic chemistry * is to discover the 
chemical conditions which are essential to the life and 
perfect developement of animals and vegetables, and, 
generally, to investigate all those processes of organic 
nature which are due to the operation of chemical laws. 

The continued existence of all living beings is depen- 
dent on the reception by them of certain substances, 
which are applied to the nutrition of their frame. An 
inquiry, therefore, into the conditions on which the life 
and growth of living beings depend, involves the study 

* Every vegetable and animal constitutes a machine of greater or 
less complexity, composed of a variety of parts dependent on each 
other, and acting all of them to produce a certain end. Vegetables 
and animals on this account are called organized beings, and the chem- 
ical history of those compounds which are. of animal or vegetable 
origin, or of organic substances, is called organic chemistry. See 
Thomson's Chemistry of Organic Bodies, and Webster's Manual of 
Chemistry, 3d edit., p. 362. 

5* 



54 OF THE CONSTITUENT ELEMENTS 

of those substances which serve them as nutriment, as 
well as the investigation of the sources whence these 
substances are derived, and the changes which ihey 
undergo in process of assimilation. 

The primary source whence man and animals derive 
the means of their growth and support is the vegetable 
kingdom. 

Plants, on the other hand, find new nutritive material 
only in inorganic substances. 

The purport of this work is to elucidate the chemical 
processes engaged in the nutrition of vegetables. 

It will be devoted to the examination of the matters 
which supply the nutriment of plants, and of the changes 
which these matters undergo in the living organism. 
The chemical compounds which afford to plants their 
principal constituents, viz. carbon and nitrogen, will 
come under consideration, as well as the relations in 
which the vital functions of vegetables stand to those of 
the animal economy and to other phenomena of nature. 



Carbon* enters into the composition of all plants, 
and of all their different parts or organs. 

The substances which constitute the principal mass of 
every vegetable are compounds of carbon with oxygen 
and hydrogen in the proper relative proportions for form- 
ing water. Woody fibre, starch, sugar, and gum, for 
example, are such compounds of carbon with the ele- 
ments of water. In another class of substances con- 
taining carbon as an element, oxygen and hydrogen are 

* Carbon is the pure inflammable principle which is the character- 
istic ingredient of all kinds of charcoal. The diamond is pure car- 
bon. Wood charcoal contains about l-50th of its weight of alkaline 
and earthy salts, which constitute the ashes when it is burned. 



OF PLANTS. 55 

again present ; but the proportion of oxygen is greater 
than would be required for producing water by union 
with the hydrogen. The numerous organic acids met 
with in plants belong, with few exceptions, to this class. 

A third class of vegetable compounds contain carbon 
and hydrogen, but no oxygen, or less of that element 
than would be required to convert all the hydrogen into 
water. These may be regarded as compounds of carbon 
with the elements of water and an excess of hydrogen. 
Such are the volatile and fixed oils, wax, and the resins. 
Many of them have acid characters. 

The juices of all vegetables contain organic acids, 
generally combined with the inorganic bases, or metallic 
oxides ; for these metallic oxides exist in every plant, 
and may be detected in its ashes after incineration. 

JsTitrogen* is an element of vegetable albumen and 

* This gas was discovered in 1772, and is called also azote or azotic 
gas, from the Greek expressive of its being incapable of supporting 
life. The name JVitrogen was given to it from its entering into the 
composition of nitric acid (aqua fortis). It has been suspected to 
be a compound, but this has not been verified. The atmosphere is 
composed of four fifths nitrogen and one fifth oxygen, not, however 
chemically united ; it also contains a ten thousandth part of carbonic 
acid and watery vapor. A mixture of oxygen and nitrogen in the 
proportions named, exhibits the general properties of the atmosphere. 
Nitrogen may be obtained from common air by removing its oxygen, 
and from the lean part of flesh meat by boiling it in diluted nitric 
acid. It unites with different proportions of oxygen, and forms as 
many distinct compounds, viz. 

c ( Protoxide of Nitrogen, nitric 
\ oxide, or exhilarating gas. 

Binoxide of Nitrogen 

or Nitric oxide. 
Hyponitrous acid. 
Nitrous acid. 
Nitric acid. 
For other details, see Webster's Chemistry, 3d edit., p. 134, «S:c. 



Ixyg. 




Mtroi_ 


100 


+ 


50 


100 


+ 


100 


100 


+ 


150 


100 


+ 


200 


100 


+ 


250 



56 OF THE CONSTITUENT ELEMENTS OF PLANTS. 

gluten* ; it is a constituent of the acids, and of what 
are termed the "indifferent substances" of plants, as 
well as of those peculiar vegetable compounds which 
possess all the properties of metallic oxides, and are 
known as " organic bases." 

Estimated by its proportional weight nitrogen forms 
only a very small part of plants, but it is never entirely 
absent from any part of them. Even when it does not 
absolutely enter into the composition of a particular part 
or organ, it is always to be found in the fluids which 
pervade it. 

It follows from the facts thus far detailed, that the de- 
velopement of a plant requires the presence, first, of 
substances containing carbon and nitrogen, and capable 
of yielding these elements to the growing organism ; 
secondly, of water and its elements ; and lastly, of a 
soil to furnish the inorganic matters which are likewise 
essential to vegetable life. 

* Gluten is the tough elastic substance which remains after the 
starch of wheat flour has been removed by washing with water. By 
putrefaction it yields an offensive odor, and when distilled furnishes 
ummonia, in this resembling some animal products. When fresh 
gluten is digested in hot alcohol, the substance is obtained which has 
been called vegetable albumen. Gluten is found in many seeds, es- 
pecially in wheat associated with albumen and starch. It is the pres- 
ence of this substance that renders wheaten flour so nutritious. The 
wheat of the South of Europe, being rich in gluten, is employed in 
the manufacture of macaroni, vermicelli, &c. 



COMPOSITION OF HUMUS. 57 



CHAPTER II. 

OF THE ASSIMILATION OF CARBON. 

The fertility of every soil is generally supposed by 
vegetable physiologists to depend on the presence in it 
of a peculiar substance to which they have given the 
name of humus. This substance, believed to be the 
principal nutriment of plants, and to be extracted by 
them from the soil in which they grow, is itself the pro- 
duct of the decay of other plants. 

Humus is described by chemists as a brown sub- 
stance, easily soluble in alkalies, but only slightly solu- 
ble in water, and produced during the decomposition of 
vegetable matters by the action of acids or alkalies. It 
has, however, received various names according to the 
different external characters and chemical properties 
which it presents. Thus, ulmin, humic acid, coal of 
humus, and humin, are names applied to modifications of 
humus. They are obtained by treating peat, woody 
fibre, soot, or brown coal with alkalies ; by decom- 
posing sugar, starch, or sugar-of-milk by means of 
acids ; or by exposing alkaline solutions of tannic and 
gallic acids to the action of the air. 

The modifications of humus which are soluble in 
alkalies, are called humic acid; while those which are 
insoluble have received the designations of humin and 
coal of humus.* 

* The soluble matters were formerly called by the eminent Swedish 
chemist Berzelius, extract of humus, and the insoluble geine (from 
the Greek yj, the earth,) also apothcme and carbonaceous humus. 



58 OF THE ASSIMILATION OF CARBON. 

The names given to these substances might cause it 
to be supposed that their composition is identical. But 
a more erroneous notion could not be entertained ; 

This substance is now known to be composed of various ingredients, 
and of these the two acids, which have received the names of Crenic 
and ^pocrenic, are particularly interesting. 

Tliese acids were discovered by Berzelius in the waters of certain 
springs in Sweden. The crenic acid was named from the Greek 
x^rivn, afounlain. It imparted to the water a yellowish color and dis- 
agreeable taste. On exposure to the air, an ochrey sediment was 
deposited which consisted chiefly of iron in the state of an oxide com- 
bined with the crenic acid. 

This acid when separated is yellow and transparent, free from 
smell, with a sharp, astringent taste, soluble in water and alcohol. 
It combines with bases and forms salts called crcnates. 

By exposure to the ah apocrenic acid is formed, — ariyfrom, denot- 
ing its origin. This acid was obtained from the ochre of the water, 
and is brown, resembling vegetable extract. 

These acids were supposed by Berzelius to occur frequently in 
water, and this has since been verified, both in Europe and in this 
country. 

The various Reports on the agriculture and geology of the United 
States contain abundant evidence that these acids exist in our soils, 
and in peat, and that the crenic acid forms soluble salts with lime. 

Ihe substances which have been called extract of humus and 
geine, some chemists have considered identical with the extract 
obtained from the bark of the elm, and the substance formed by fusing 
sawdust with potash. Others view the principal part of those sub- 
stances as a compound of the crenic and apocrenic acids with bases, 
such as lime, magnesia, oxide of iron, &c. Apocrenic acid forms an 
insoluble substance with lime; crenic acid forms soluble compounds 
with alkalies, and these acids have been found in soils and peat in 
Rhode Island, Maine, and New Hampshire. The crenate of lime 
exists in the subsoil. (Dr. C. T. Jackson.) 

Dr. Thomson is of opinion that there are various species of this 
substance, differing from each other according to the plants from 
which it has been derived. He slates the proportion of" apotheme " 
in an analysis of wheat to have been about 20^ per cent. 

Although by chemical analysis the substance which has been called 
geine has been ascertained to be a compound, there will be conven- 



COMPOSITION OF HUMUS. 



59 



since even sugar, acetic acid, and colophan (rosin) do 
not differ more widely in the proportions of their con- 

ience perhaps in retaining the term to express the mass of uutritive 
matters which soils and composts afford. Dr. S. L. Dana considers 
geine as forming tiie basis of all the nourishing part of all vegetable 
manures, and in the three states of " vegetable extract, geine, and 
carbonaceous mould " to be the principle which gives fertility to soils 
long after the action of common manures has ceased. See Report on 
the reexamination of the Economical Geology of Massachusetts. In 
the Third Report on the .Agriculture of the Slate of Massachusetts, 
1840, Dr. Dana remarks, that geine " is the decomposed organic mat- 
ter of the soil. It is the product of putrefaction ; continually sub- 
jected to air and moisture, it is finally wholly dissipated in air, leaving 
only the inorganic bases of the plant, with which it was once com- 
bined. Now whether we consider this as a simple substance, or 
composed of several others, called crenic, apocrenic, puteanic, ulmic 
acids, glairin, apotheme, extract, humus, or mould, agriculture ever 
has, and probably ever will consider it one and the same thing, re- 
quiring always similar treatment to produce it; similar treatment to 
render it soluble when produced ; similar treatment to render it an 
effectual manure. It is the end of all compost heaps to produce solu- 
ble geine, no matter how compound our chemistry may teach this 
substance to be." page 191. 

Dr. Dana has given the following as the average quantity of 
" geine '" in the different geological varieties of the soils of Massachu- 
setts : 

Soluble Geine. 
2.25 



Insoluble Geine 

2.15i^ 



Soil. 
Alluvium, 

Tertiary Argillaceous, 3.94 

Sandstone, 3.28 

Graywacke, 3.60 

Argillaceous Slate, 5.77 

Limestone, 3 40 

Mica Slate, 4.34 

Talcose Slate, 3.67 

Gneiss, 4.30 

Granite, 4.05 

Sienite, 4.40 

Porphyry, 5 97 

Greenstone, 4.56 
See Professor Hitchcock's Report, and ^American Journal of Science^ 
Vol. XXXVI, Art. XII. 




60 OF THE ASSIMILATION OF CARBON. 

stiluent elements, than do the various nnodifications of 
hwnus. 

Humic acid formed by the action of hydrate * of 
potash upon sawdust contains, according to the accurate 
analysis of Peligot, 72 per cent, of carbon, while the 
humic acid obtained from turf and brown coal contains, 
according to Sprengel, only 58 per cent. ; that pro- 
duced by the action of dilute sulphuric acid upon sugar, 
57 per cent, according to Malaguti ; and that, lastly, 
which is obtained from sugar or from starch, by means 
of muriatic acid, according to the analysis of Stein, 64 
per cent. All these analyses have been repeated with 
care and accuracy, and the proportion of carbon in the 
respective cases has been found to agree with the esti- 
mates of the different chemists above mentioned ; so 
that there is no reason to ascribe the difference in this 
respect between the varieties of humus to the mere dif- 
ference in the methods of analysis or degrees of expert- 
ness of the operators. Malaguti states, moreover, that 
humic acid contains an equal number of equivalents of 
oxygen and hydrogen, that is to say, that these elements 
exist in it in the proportions for forming water ; while, 
^''%^^^^rding to Sprengel, the oxygen is in excess, and 
^V^^igot even estimates the quantity of oxygen at 14 
%vVSqiiivalents, and the hydrogen at only 6 equivalents, 
^■C*MW^""g tlie deficiency of hydrogen as great as 8 equiva- 

^J'JrTtLis quite evident, therefore, that chemists have been 
•^ISwhe habit of designating all products of the decompo- 

4tt%^ 

^^j^j^HyHmips are compounds of oxides, sails, «&c. with definite quan- 

^*^3h'^ °^ water, — a substance from wliich all the water has been 
. , T,^^©iMoved is anhydrous. Even after exposure to a red heat caustic 
potash retains water. 



PROPERTIES OF HUMUS. 61 

sition of organic bodies which had a brown or brownish 
blacl< color by the names of hnmic acid or hnmin, ac- 
cording as they were soluble or insoluble in alkalies ; 
although in their composition and mode of origin, the 
substances thus confounded might be in no way allied. 

Not the slightest ground exists for the belief that one 
or other of these artificial products of the decomposi- 
tion of vegetable matters exists in nature in the form 
and endowed with the properties of the vegetable con- 
stituents of mould ; there is not the shadow of a proof 
that one of them exerts any influence on the growth of 
plants either in the way of nourishment or otherwise. 

Vegetable physiologists have, without any apparent 
reason, imputed the known properties of the humus 
and humic acids of chemists to that constituent of mould 
which has received the same name, and in this way 
have been led to their theoretical notions respecting the 
functions of the latter substance in vegetation. 

The opinion that the substance called humus is ex- 
tracted from the soil by the roots of plants, and that 
the carbon entering into its composition serves in some 
form or other to nourish their tissues, is so general and 
so firmly established, that hitherto any new argument 
in its favor has been considered unnecessary ; the obvi- 
ous difference in the growth of plants according to the 
known abundance or scarcity of Jnimus in the soil, 
seemed to afford incontestable proof of its correctness. 

Yet, this position, when subn)itted to a strict examina- 
tion, is found to be untenable, and it becomes evident 
from most conclusive proofs that humus in the form in 
which it exists in the soil does not yield the smallest 
nourishment to plants. 

The adherence to the above incorrect opinion has 
- • • » ^ 



. > _r 



-: V 



62 OF THE ASSIMILATION OF CARBON. 

hitherto rendered it impossible for the true theory of 
the nutritive process in vegetables to become known, 
and has thus deprived us of our best guide to a rational 
practice in agriculture. Any great improvement in that 
most important of all arts is inconceivable without a 
deeper and more perfect acquaintance with the sub- 
stances which nourish plants, and with the sources 
whence they are derived ; and no other cause can be 
discovered to account for the fluctuating and uncertain 
state of our knowledge on this subject up to the present 
time, than that modern physiology has not kept pace 
with the rapid progress of chemistry. 

In the following inquiry we shall suppose the hwmis 
of vegetable physiologists to be really endowed with 
ihe properties recognised by chemists in the brownish 
black deposites which they obtain by precipitating an 
alkaline decoction of mould or peat by means of acids, 
and which they name hvmic acid.* 

* The extract obtained by Berzelius from black, brownish soils has 
been designated as humic extract, in some cases with a substance 
called glairin. The glairin is described by Thomson as a pe- 
culiar substance wliich has been observed in certain sulphureous 
♦ mineral waters, and was first noticed by Vauquelin (jinn, de Chim. 
XXXIX. 173), who described several of its properties and considered 
it analogous to gelatin. An account of it was drawn tip by M, An- 
glada, of Montpellier, and communicated to the Royal Academy of 
Medicine of Paris, in 1827. It gelatinizes with water when suffi- 
ciently concentrated. Sometimes it is white, and at others of a red 
color ; when dried it shrinks to g^th of its bulk when moist. It satu- 
rates ammonia, and decomposes several metallic salts. It is destitute 
of smell and taste. It does not glue substances together like gelatin 
and albumen, it yields ammonia by decomposition, and is capable 
of putrefaction like animal bodies. The general opinion is, that it is 
of vegetable origin, and allied to the genus f/-cr/ic//a, though its ex- 
istence in mineral waters has not been accounted for. Thomson's 
Oriranic Ckemislru, (I'M. I found it very abundant about the iiot 
sulphureous waters of the island of St. Michael, Azores._^ */f 4^f»4it. 



ABSORPTION OF HUMUS. 63 

Humic acid, when first precipitated, is a flocculent 
substance, is soluble in 2500 times its weight of water, 
and combines with alkalies, lime and magnesia, forming 
compounds of the same degree of solubility. (Spren- 

gel.) 

Vegetable physiologists agree in the supposition 
that by the aid of water humus is rendered capable of 
being absorbed by the roots of plants. But according 
to the observation of chemists, humic acid is soluble 
only when newly precipitated, and becomes completely 
insoluble when dried in the air, or when exposed in the 
moist state to the freezing temperature. (Sprengel.) 

Both the cold of winter and the heat of summer 
therefore are destructive of the solubility of humic acid, 
and at the same time of its capability of being assimi- 
lated by plants. So that, if it is absorbed by plants, 
it must be in some altered form.* 

The correctness of these observations is easily de- 
monstrated by treating a portion of good mould with 
cold water. The fluid remains colorless, and is found 
to have dissolved less than 100,000 part of its weight 
of organic matters, and to contain merely the salts which 
are present in rain-water. 

Decayed oak-wood, likewise, of which humic acid is 
the principal constituent, was found by Berzelius to 
yield to cold water only slight traces of soluble mate- 
rials ; and I have myself verified this observation on 
the decayed wood of beech and fir. 

These facts, which show that humic acid in its un- 

* According to Dr. Jackson, the substances contained in humic 
extract form soluble salts with lime. The acids form soluble salts 
with the same substance, and the salts are decomposed in the process 
of vegetation. 



64 OF THE ASSIMILATION OF CARBON. 

altered condition cannot serve for the nourishment of 
plants, have not escaped the notice of physiologists ; 
and hence they have assumed that the lime or the 
different alkalies found in the ashes of vegetables render 
soluble the humic acid and fit it for the process of 
assimilation. 

Alkalies and alkaline earihs do exist in the different 
kinds of soil in sufficient quantity to form such soluble 
compounds with the humic acid. 

Now, let us suppose that humic acid is absorbed by 
plants in the form of that salt which contains the largest 
proportion of humic acid, namely, in the form of humate 
of lime, and then from the known quantity of the alka- 
line bases contained in the ashes of plants, let us calcu- 
late the amount of humic acid which might be assimilated 
in this manner. Let us admit, likewise, that potash, 
soda, and the oxides of iron and manganese have the 
same capacity of saturation as lime with respect to hu- 
mic acid, and then we may take as the basis of our 
calculation the analysis of M. Berthier, who found that 
1000 lbs. of dry fir-wood yielded 4 lbs. of ashes, and 
that in every 100 lbs. of these ashes, after the chloride 
of potassium and sulphate of potash were extracted, 
53 lbs. consisted of the basic metallic oxides, potash, 
soda, lime, magnesia, iron, and manganese. 

40,000 square feet* Hessian measure of wood-land 
yield annually, according to Dr. Heyer, on an average, 
2650 lbs. Hessian of dry fir-wood, which contain 5*6 lbs. 
Hessian of metallic oxides. 

* [The numbers in the text in Hessian feet and pounds will show 
a proportion to other numbers equally well as if they were reduced 
to their equivalents in Knijlisli. For those, however, who prefer 
knowing the exact English quantities, a table of equivalents is given 
at the end. — P.] 



ABSORPTION OF HUMUS. 65 

Now, according to the estimates of Malaguti and 
Sprengel, 1 lb. Hessian of lime combines chemically 
with 10-9 lbs. Hessian of humic acid ; 5-6 lbs. of the 
metallic oxides would accordingly introduce into the 
trees 61 lbs. Hessian of humic acid, which, admitting 
humic acid to contain 58 per cent, of carbon, would 
correspond to 91 lbs. Hessian of dry wood. But 
we have seen that 2650 lbs. of fir-wood are really 
produced. 

Again, if the quantity of humic acid which might be 
introduced into wheat in the form of humates is calculat- 
ed from the known proportion of metallic oxides exist- 
ing in wheat straw, (the sulphates and chlorides also 
contained in the ashes of the straw not being included,) 
it will be found that the wheat growing on 40,000 square 
feet of land would receive in that way 571 lbs. Hessian 
of humic acid, corresponding to 85 lbs. Hessian of 
woody fibre. But the extent of land just mentioned 
produces, independently of the roots and grain, 1780 
lbs. Hessian of straw, the composition of which is the 
same as that of woody fibre. 

It has been taken for granted in these calculations 
that the basic metallic oxides which have served to 
introduce humic acid into the plants do not return to 
the soil, since it is certain that they remain fixed in the 
parts newly formed during the process of growth. 

Let us now calculate the quantity of humic acid 
which plants can receive under the most favorable cir- 
cumstances, viz through the agency of rain-water. 

The quantity of rain which falls at Erfurt, one of the 

most fertile districts of Germany, during the months of 

April, May, June, and July, is stated by Schubler to 

be 17| lbs. Hessian over every square foot of surface ; 

6* 



66 OF THE ASSIMILATION OF CARBON. 

40,000 square feet consequently receive 700,000 lbs. 
Hessian of rain-water. 

If, now, we suppose that the whole quantity of this 
rain is taken up by the roots of a summer plant which 
ripens four months after it is planted, so that not a 
pound of this water evaporates except from the leaves 
of the plant ; and if we further assume that the water 
thus absorbed is saturated with humale of lime (the 
most soluble of the bumates, and that which contains 
the largest proportion of humic acid) ; then the plants 
thus nourished would not receive more than 300 lbs. 
Hessian of humic acid, since one part of humate of 
lime requires 2500 parts of water for solution. 

But the extent of land which we have mentioned 
produces 2580 lbs. Hessian of corn (in grain and straw, 
the roots not included,) or 20,000 lbs. Hessian of beet- 
root (without the leaves and small radicle fibres). It is 
quite evident that the 300 lbs. of humic acid, supposed 
to be absorbed, cannot account for the quantity of car- 
bon contained in the roots and leaves alone, even if the 
supposition were correct, that the whole of the rain- 
water was absorbed by the plants. But since it is 
known that only a small portion of the rain-water which 
falls upon the surface of the earih evaporates through 
plants, the quantity of carbon which can be conveyed 
into them in any conceivable manner by means of humic 
acid must be extremely trifling in comparison with that 
actually produced in vegetation. 

Other considerations, of a higher nature, confute the 
common view respecting the nutritive office of humic 
acid, in a manner so clear and conclusive that it is 
difficult to conceive how it could have been so generally 
adopted. 



CARBON IN WOOD, &C. 6.7 

Fertile land produces carbon in the fornri of wood, 
hay, grain, and other kinds of growth, the masses of 
which differ in a rennarkable degree. 

2650 lbs. Hessian of firs, pines, beeches, &c. grow 
as wood upon 40,000 square feet of forest-land, with 
an average soil. The same superficies yields 2500 lbs. 
Hessian of hay. 

•A similar surface of corn-land gives from 18,000 to 
20,000 lbs. Hessian of beet-root, or 800 lbs. Hessian 
of rye, and 1780 lbs. Hessian of straw, 160 sheaves 
of 14 lbs. Hessian each, in all, 2580 lbs. Hessian. 

One hundred parts of dry fir-wood contain 38 parts 
of carbon ; therefore, 2650 lbs. contain 1007 lbs. Hes- 
sian of carbon. 

One hundred parts of hay,* dried in air, contain 
44*31 parts carbon. Accordingly, 2500 lbs. of hay 
contain 1008 lbs. Hessian of carbon. 

Beet-roots contain from 89 to 89-5 parts water, and 
from 10*5 to 11 parts solid matter, which consists of 
from 8 to 9 per cent, sugar, and from 2 to 2| per cent, 
cellular tissue. Sugar contains 42*4 per cent. ; cellular 
tissue, 47 per cent, of carbon. 

20,000 lbs. of beet-root, therefore, if they contained 
9 per cent, of sugar, and 2 per cent, of cellular tissue, 
would yield 936 lbs. Hessian of carbon, of which 756 
lbs. Hessian would be due to the sugar, and 180 lbs. 
Hessian to the cellular tissue ; the carbon of the leaves 
and small roots not being included in the calculation. 



» 100 parts of hay, dried at 100° C. (212" F.) and burned with oxide 
of copper in a stream of oxygen gas, yielded 51-93 water, 165-8 car- 
bonic acid, and 0-82 of ashes. This gives 45-87 carbon, 5-76 hydrogen, 
31-55 ogygen, and 6-82 ashes. Hay, dried in the air, loses 11-2 p. c. 
water at 100° C. (212° F.) — Dr. Win. 



§8 OF THE ASSIMILATION OF CARBON. 

One hundred parts of straw,* dried in air, contain 
38 per cent, of carbon ; therefore 1780 lbs. of straw 
contain G76 lbs. Hessian of carbon. One hundred 
parts of corn contain 43 parts of carbon ; 800 lbs. must 
therefore contain 344 lbs. Hessian; — in all, 1020 lbs. 
Hessian of carbon. 

40,000 square feet of wood and meadow land pro- 
duce, consequently, 1007 lbs. of carbon ; while the 
same extent of arable land yields in beet-root, without 
leaves, 936 lbs. ; or in corn, 1020 lbs. 

It must be concluded from these incontestable facts, 
that equal surfaces of cultivated land of an average 
fertility produce equal quantities of carbon : yet, how 
unlike have been the different conditions of the growth 
of the plants from which this has been deduced ! 

Let us now inquire whence the grass in a meadow, 
or the wood in a forest receives its carbon, since there 
no manure, — no carbon, — has been given to it as 
nourishment ? and how it happens, that the soil, thus 
exhausted, instead of becoming poorer, becomes every 
year richer in this element ? 

A certain quantity of carbon is taken every year from 
the forest or meadow, in the form of wood or hay, and, 
in spite of this, the quantity of carbon in the soil aug- 
ments ; it becomes richer in humus. 

It is said, that in fields and orchards all the carbon 
which may have been taken away as herbs, as straw, as 
seeds, or as fruit, is replaced by means of manure ; and 
yet this soil produces no more carbon than that of the 

* Straw analyzed in the same manner, and dried at ICO" C, gave 
46-37 p. c. of carbon, 5()8 p. c. of hydrogen, 4;l-93 p. c. of oxygen, 
and 4 02 p. c. of ashes. Straw, dried in the air, at 100" C. lost 18 p. c. 
of water. — Dr. Will. 



ORIGIN OF CARBON. 69 

forest or meadow where it is never replaced. It cannot 
be conceived that the laws for the nutrition of plants are 
changed by culture, — that the sources of carbon for 
fruit or grain, and for grass or trees, are different. 

It is not denied that manure exercises an influence 
upon the developement of plants ; but it may be affirm- 
ed with positive certainly, that it neither serves for the 
production of the carbon, nor has any influence upon it, 
because we find ti)at the quantity of carbon produced by 
manured lands is not greater than that yielded by lands 
which are not manured. The discussion as to the man- 
ner in which manure acts has nothing to do with the 
present question, which is the origin of the carbon. 
The carbon must be derived from other sources ; and 
as the soil does not yield it, it can only be extracted 
from the atmosphere. 

In attempting to explain the origin of carbon in plants, 
it has never been considered that the question is inti- 
mately connected with that of the origin of humus. It 
is universally admitted that humus arises from the decay 
of plants. No primitive humus, therefore, can have 
existed ; for plants must have preceded the humus. 

Now, whence did the first vegetables derive their car- 
bon ? and in what form is the carbon contained in the 
atmosphere ? 

These two questions involve the consideration of two 
most remarkable natural phenomena, which by their re- 
ciprocal and uninterrupted influence, maintain the life of 
the individual animals and vegetables, and the continued 
existence of both kingdoms of organic nature. 

One of these questions is connected with the invaria- 
ble condition of the air with respect to oxygen. One 
hundred volumes of air have been found, at every peri- 



70 OF THE ASSIMILATION OP CARBON. 

od and in every climate, to contain twenty-one volumes 
of oxygen, with such small deviations, that they must be 
ascribed to errors of observation. 

Although the absolute quantity of oxygen contained 
in the atmosphere appears very great when represented 
by numbers, yet it is not inexhaustible. One man con- 
sumes by respiration 45* Hessian cubic feet of oxygen 
in 24 hours ; 10 centners of charcoal consume 58,112 
cubic feet of oxygen during its combustion ; and a small 
town like Giessen (with about 7000 inhabitants) extracts 
yearly from the air, by the wood employed as fuel, 
more than 1000 millions of cubic feet of this gas. 

When we consider facts such as these, our former 
statement, that the quantity of oxygen in the atmosphere 
does not diminish in the course of agesf , — • that the air 
at the present day, for example, does not contain less 
oxygen than that found in jars buried for 1800 years in 
Pompeii, — appears quite incomprehensible, unless some 
source exists whence the oxygen abstracted is replaced. 
How does it happen, then, that the proportion of oxy- 
gen in the atmosphere is thus invariable ? 

The answer to this question depends upon another ; 

* [For the proportions in English weights and measures see the ta- 
ble at the end of the volume.] 

t The air contains, in maximo, lOififoo carbonic acid gas and loosoo 
oxygeji gas. A man consumes, in one year, 1GC,075 cubic feet of 
gas (or 45,000 cubic inches in one day, according to Lavoisier, Seguin. 
and Davy) ; a tliousand million men must accordingly consume ICG 
billion cubic feet in one year; this is equal to looo of ^'^^ quantity 
which is contained in the air in the form of carbonic acid. Tlie car- 
bonic acid in the air would thus be doubled in 1000 years, and man 
alone would exhaust all the oxygen, and convert it into carbonic acid 
in 303 times as many years. The consumption by animals, and by 
the process of combustion, is not introduced into the calculation. 



ITS PROPORTION IN THE ATMOSPHERE. 71 

namely, what becomes of the carbonic acid, which is 
produced during the respiration of animals, and by the 
process of combustion ? A cubic foot of oxygen gas, by 
uniting with carbon so as to form carbonic acid, does 
not change its volume. The billions of cubic feet of 
oxygen extracted from the atmosphere, produce the 
same number of billions of cubic feet of carbonic acid, 
which immediately supply its place. 

The most exact and most recent experiments of De 
Saussiire, made in every season, for a space of three 
years, have shown, that the air contains on an average 
0.000415 of its own volume of carbonic acid gas ; so 
that, allowing for the inaccuracies of the experiments, 
which must diminish the quantity obtained, the propor- 
tion of carbonic acid in the atmosphere may be regarded 
as nearly equal to 1-1000 part of its weight. The quan- 
tity varies according to the seasons ; but the yearly av- 
erage remains continually the same. 

We have no reason to believe that this proportion 
was less in past ages ; and nevertheless, the in)mense 
masses of carbonic acid, which annually flow into the 
atmosphere from so many causes, ought perceptibly to 
increase its quantity from year to year. But we find, 
that all earlier observers describe its volume as from 
one half to ten times greater than that which it has at the 
present time ; so that we can hence at most conclude, 
that it has diminished. 

It is quite evident, that the quantities of carbonic acid 
and oxygen in the atmosphere, which remain unchanged 
by lapse of time, must stand in some fixed relation to 
one another ; a cause must exist which prevents the 
increase of carbonic acid, by removing that which is 
constantly forming ; and there must be some means of 



72 OF THE ASSIMILATION OF CARBON. 

replacing the oxygen, which is removed from the air by 
the processes of combustion and putrefaction, as well as 
by the respiration of animals. 

Both these causes are united in the process of vege- 
table life. 

The facts which we have stated in the preceding 
pages prove, that the carbon of plants must be derived 
exclusively from the atmosphere. Now, carbon exists 
in the atmosphere only in the form of carbonic acid ; 
and, therefore, in a state of combination with oxygen. 

It has been already mentioned likewise, that carbon 
and the elements of water form the principal constitu- 
ents of vegetables ; the quantity of the substances which 
do not possess this composition being in very small pro- 
portion. Now, the relative quantity of oxygen in the 
whole mass is less than in carbonic acid. It is therefore 
certain, that plants must possess the power of decom- 
posing carbonic acid, since they appropriate its carbon 
for their own use. The formation of their principal 
component substances must necessarily be attended with 
the separation of the carbon of the carbonic acid from 
the oxygen, which must be returned to the atmosphere, 
whilst the carbon enters into combination with water or 
its elements. The atmosphere must thus receive a vol- 
ume of oxygen for every volume of carbonic acid which 
has been decomposed. 

This remarkable property of plants has been demon- 
strated in the most certain manner, and it is in the power 
of every person to convince himself of its existence. 
The leaves and other green parts of a plant absorb car- 
bonic acid, and emit an equal vx)lume of oxygen. They 
possess this property quite independently of the plant ; 
for if, after being separated from the stem, they are 



ITS SOURCE, THE ATMOSPHERE. 73 

placed in water containing carbonic acid, and exposed 
in that condition to the sun's hght, the carbonic acid is, 
after a time, found to have disappeared entirely from the 
water. If the experiment is conducted under a glass 
receiver filled with water, the oxygen emitted from the 
plant may be collected and examined. When no more 
oxygen gas is evolved, it is a sign that all the dissolved 
carbonic acid is decomposed ; but the operation recom- 
mences if a new portion of it is added. 

Plants do not emit gas when placed in water which 
either is free from carbonic acid, or contains an alkali 
that protects it from assimilation. 

These observations were first made by Priestley and 
Sennebier. The excellent experiments of De Saussure 
have further shown, that plants Increase in weight during 
the decomposition of carbonic acid and separation of 
oxygen. This increase in weight is greater than can be 
accounted for by the quantity of carbon assimilated ; a 
fact which confirms the view, that the elements of water 
are assimilated at the same time. 

The life of plants is closely connected with that of 
animals, in a most simple manner, and for a wise and 
sublime purpose. 

The presence of a rich and luxuriant vegetation may 
be conceived without the concurrence of animal life, 
but the existence of animals is undoubtedly dependent 
upon the life and development of plants. 

Plants not only afford the means of nutrition for the 
growth and continuance of animal organization, but they 
likewise furnish that which is essential for the support of 
the important vital process of respiration ; for besides 
separating all noxious matters from the atmosphere, they 
are an inexhaustible source of pure oxygen, which sup- 



74 OF THE ASSIMILATION OF CARBON. 

plies the loss which the air is constantly sustaining. An- 
imals, on the other hand, expire carbon, which plants 
inspire ; and thus the composition of the medium in 
which both exist, namely, the atmosphere, is maintained 
constantly unchanged. 

It may be asked. Is the quantity of carbonic acid in 
the atmosphere, which scarcely amounts to 1-1 0th per 
cent., sufficient for the wants of the whole vegetation on 
the surface of the earth, — is it possible that the carbon 
of plants has its origin from the air alone ? This ques- 
tion is very easily answered. It is known that a column 
of air, of 2216-66 lbs. weight, Hessian measure, rests 
upon every square Hessian foot of the surface of the 
earth ; the diameter of the earth and its superficies are 
likewise known, so that the weight of the atmosphere 
can be calculated with the greatest exactness. The 
thousandth part of this is carbonic acid, which contains 
upwards of 27 per cent, carbon. By this calculation it 
can be shown, that the atmosphere contains 3000 billion 
Hessian lbs. of carbon ; a quantity which amounts to 
more than the weight of all the plants, and of all the 
strata of mineral and brown coal, which exist upon the 
earth. This carbon is, therefore, more than adequate 
to all the purposes for which it is required. The quan- 
tity of carbon contained in sea-water, is proportionally 
still greater. 

If, for the sake of argument, we suppose the su- 
perficies of the leaves and other green parts of plants, 
by which the absorption of carbonic acid is effected, 
to be double that of the soil upon which they grow, 
a supposition which is much under the truth in the 
case of woods, meadows, and corn fields ; and if we 
further suppose that carbonic acid equal to 0*00067 of 



ITS SOURCE, THE ATMOSPHERE. 75 

the volume of the air, or 1-1 000th of its weight is ab- 
stracted from it during every second of time, for eight 
hours daily, by a field of 80,000 Hessian square feet ; 
then those leaves would receive 1000 Hessian lbs. of 
carbon in 200 days.* 

But it is inconceivable, that the functions of the or- 
gans of a plant can cease for any one moment during its 
life. The roots and other parts of it, which possess 
the same power, absorb constantly water and carbonic 
acid. This power is independent of solar light. Dur- 
ing the day, when the plants are in the shade, and dur- 
ing the night, carbonic acid is accumulated in all parts 
of their structure ; and the assimilation of the carbon 
and the exhalation of oxygen commence from the in- 
stant that the rays of the sun strike them. As soon as 
a young plant breaks through the surface of the ground, 

* The quantity of carbonic acid which can be extracted from the 
air in a given lime, is shown by the following calculation. During the 
whitewashing of a small chamber, the superficies of the walls and roof 
of which we will suppose to be 105 square metres, and which receives 
six coats of lime in four days, carbonic acid is abstracted from the air, 
and the lime is consequently converted, on the surface, into a carbon- 
ate. It has been accurately determined that one square decimetre re- 
ceives in this way, a coating of carbonate of lime which weighs 0'732 
grammes. Upon the 105 square metres, already mentioned, there 
must accordingly be formed 7686 grains of carbonate of lime, which 
contain 4325-6 grains of carbonic acid. The weight of one cubic de- 
cimetre of carbonic acid being calculated at two grammes, (more ac- 
curately 1-97978,) the above mentioned surface must absorb in four 
days 2 163 cubic metres of carbonic acid. 2500 square metres (one 
Hessian acre) would absorb, under a similar treatment, 51.^ cubic 
metres = 3296 cubic feet of carbonic acid in four days. In 200 days 
it would absorb 2375 cubic metres = 164,800 cubic feet, which con- 
tain 10,300 lbs. Hessian of carbonic acid of which 2997 lbs. are car- 
bon, a quantity three times as great as that which is assimilated by 
the leaves and roots growing upon the same space. — L. 



76 OF THE ASSIMILATION OF CARBON. 

it begins to acquire color from the top downwards ; and 
the true formation of woody tissue commences at the 
same time.* 

The proper, constant, and inexhaustible sources of 
oxygen gas are the tropics and warm climates, where a 
sky, seldom clouded, permits the glowing rays of the 
sun to shine upon an immeasurably luxuriant vegetation. 
The temperate and cold zones, where artificial warmth 
must replace deficient heat of the sun, produce, on the 
contrary, carbonic acid in superabundance, which is 
expended in the nutrition of the tropical plants. The 
same stream of air, which moves by the revolution of 
the earth from the equator to the poles, brings to us, in 
its passage from the equator, the oxygen generated 
there, and carries away the carbonic acid formed duiing 
our winter f . 

The experiments of De Saussure have proved, that 
the upper strata of the air contain more carbonic acid 
than the lower, which are in contact with plants ; and 

* Plants that grow in tlie dark are well known to be colorless. 
This is seen in the blanching of celery (etiolation), the earth is heap- 
ed around the stalks to exclude the light. 

t The objection has been urged that towards the end of autumn 
and through the winter and early spring the air in our climate must 
become impure, from the absence of leaves, — that the oxygen 
must diminish and carbonic acid increase in the atmosphere. But 
the different parts of the atmosphere are constantly mixed together by 
the winds, which, when strong, move at the rate of from GO to 100 
miles an hour. There are, too, the vast forests and savannas in 
tropical climates always luxuriant in vegetation, and the air from 
them passing often over the ocean or other large surfaces of water, 
arrives in an uncontaminated state. The storms and tempests which 
occur have also a salutary influence. By constant agitation and mo- 
tion the equilibrium of the constituent parts of the atmosphere is thus 
preserved. 



ITS SOURCE, THE ATMOSPHERE. 77 

that the quantity is greater by night than by day, when 
it undergoes decomposition. 

Plants thus improve the air, by the removal of car- 
bonic acid, and by the renewal of oxygen, which is 
immediately applied to the use of man and animals. 
The horizontal currents of the atmosphere bring with 
them as much as they carry away, and the interchange 
of air between the upper and lower strata, which their 
difference of temperature causes, is extremely trifling 
when compared with the horizontal movements of the 
winds. Vegetable culture heightens the healthy state 
of a country, and a previously healthy country would 
be rendered quite uninhabitable by the cessation of all 
cultivation. 

The most important function in the life of plants, or 
in other words, in their assimilation of carbon, is the 
separation, we might almost say the generation, of ox- 
ygen. No matter can be considered as nutritious, or 
as necessary to the growth of plants, which possesses a 
composition either similar to or identical with theirs, 
and the assimilation of which, therefore, could take 
place without exercising this function. 

We have satisfactory proofs that decayed woody 
fibre (humus) contains carbon and the elements of wa- 
ter, without an excess of oxygen ; its composition 
differing from that of woody fibre, in its being richer in 
carbon. 

Vegetable physiologists consider the formation of 
woody fibre from humus as very simple ; they say, 
humus has only to enter into chemical combination with 
water, in order to efi'ect the formation of woody fibre, 
starch, or sugar.* 

* Meyen, Pflanzenphysiologie, ii. s. 141. 
7 * 



78 OF THE ASSIMILATION OF CARBON. 

But the same philosophers have informed us, that 
aqueous solutions of sugar, starch, and gum, are im- 
bibed by the roots of plants, and carried to all parts of 
their structure, but are not assimilated ; they cannot, 
therefore, be employed in their nutrition. We could 
scarcely conceive a form more convenient for assimila- 
tion than that of gum, starch, and sugar, for they all 
contain the elements of woody fibre, and nearly in the 
same proportiojis. 

All the erroneous opinions concerning the modus 
operandi of humus have their origin in the false notions 
entertained respecting the most important vital functions 
of plants ; analogy, that fertile source of error, having 
unfortunately led to the very unapt comparison of the 
vital functions of plants with those of animals. 

Substances such as sugar, starch, &c., which contain 
carbon and the elements of water, are products of the 
life of plants, which live only whilst they generate them. 
The same may be said of humus, for it can be formed 
in plants, like the former substances. Smithsun, Jame- 
son^ and Thomson, found that the black excretions of 
unhealthy elms, oaks, and horse-chesnuts, consisted of 
humic acid in combination with alkalies. Berzclius 
detected similar products in the bark of most trees. 
Now, can it be supposed, that the diseased organs of a 
plant possess the power of generating the matter, to 
which its sustenance and vigor are ascribed ? 

How does it happen, it may be asked, that the ab- 
sorption of carbon from the atmosphere by plants is 
doubted by all botanists and vegetable physiologists, 
and that by the greater number the purification of the 
air by means of them is wholly denied '' 

These doubts have arisen from the action of plants on 
the air in the absence of light, that is, during the night. 



INFLUENCE OF THE SHADE ON PLANTS. 79 

The experiments of Ingenhouss were in a great meas- 
ure the cause of this uncertainty of oj3inion, regarding 
the influence of plants in purifying the air. His obser- 
vation, that green plants emit carbonic acid in the dark, 
led De Saiissure and Grischow to new investigations, 
by which they ascertained that under such conditions 
plants do really absorb oxygen, and emit carbonic acid ; 
but that the whole volume of air undergoes diminution 
at the same time. From the latter fact it follows, that 
the quantity of oxygen gas absorbed is greater, than the 
volume of carbonic acid separated ; for if this were not 
the case, no diminution could occur. These facts 
cannot be doubted, but the views based on them have 
been so false, that nothing, except the total want of ob- 
servation, and the utmost ignorance of the chemical 
relations of plants to the atmosphere, can account for 
their adoption. 

It is known, that nitrogen, hydrogen, and a number 
of other gases, exercise a peculiar, and, in general, an 
injurious influence upon living plants. Is it then, prob- 
able, that oxygen, one of the most energetic agents 
in nature, should remain without influence on plants 
when one of their peculiar processes of assimilation has 
ceased ? 

It is true, that the decomposition of carbonic acid is 
arrested by absence of light. But then, namely, at 
night, a true chemical process commences, in conse- 
quence of the action of the oxygen in the air, upon the 
organic substances composing the leaves, blossoms, and 
fruit. This process is not at all connected wiih the 
life of the vegetable organism, because it goes on in a 
dead plant exactly as in a living one. 

The substances composing the leaves of different 



/ 

\ 



80 OF THE ASSIMILATION OF CARBON. 

plants being known, it is a matter of the greatest ease 
and certainty, to calculate which of them, during life, 
should absorb most oxygen by chemical action, when 
the influence of light is withdrawn. 

The leaves and green parts of all plants, containing 
volatile oils or volatile constituents in general, which 
change into resin by the absorption of oxygen, should 
absorb more than other parts which are free from such 
substances. Those leaves, also, which contain either 
the constituents of nut-galls, or compounds, in which 
nitrogen is present, ought to absorb more oxygen than 
those which do not contain such matters. The correct- 
ness of these inferences has been distinctly proved by 
the observations of De Saussiire ; for, whilst the taste- 
less leaves of the Agave Jlmcricana absorb only 0.3 of 
their volume of oxygen, in the dark, during 24 hours, 
the leaves of the Pinus Abies, which contain volatile 
and resinous oils, absorb 10 times, those of the Quercus 
Robur containing tannic acid 14 times, and the balmy 
leaves of the Populus nlba 21 times that quantity. 
This chemical action is shown, very plainly, also in the 
leaves of the Cotyledon calycinum, the Cocalia Jicoules 
and others ; for they are sour like sorrel in the morning, 
tasteless at noon, and bitter in the evening. The for- 
mation of acids is effected during the night, by a true 
process of oxidation : these are deprived of their acid 
properties during the day and evening, and are changed, 
by separation of a part of their oxygen, into con)pounds 
containing oxygen and hydrogen, either in the same pro- 
portions as in water, or even with an excess of hydro- 
gen, which is the composition of all tasteless and bitter 
substances. 

Indeed, the quantity of oxygen absorbed could be 



INFLUENCE OF THE SHADE ON PLANTS. 81 

estimated pretty nearly, by the different periods, wliich 
the green leaves of plants require to undergo alteration 
in color, by the influence of the atmosphere. Those 
which continue longest green, will abstract less oxygen 
from the air in an equal space of time, than those, the 
constituent parts of which suffer a more rapid change. 
It is found, for example, that the leaves of the Ilex aqui- 
folhim, distinguished by the durability of their color, 
absorb only 0.86 of their volume of oxygen gas, in the 
same time that the leaves of the poplar absorb 8, and 
those of the beech 9| times their volume ; both the beech 
and poplar being remarkable for the rapidity and ease 
with which the color of their leaves changes. 

When the green leaves of the poplar, the beech, the 
oak, or the holly, are dried under the air-pump, with ex- 
clusion of light, then moistened with water, and placed 
under a glass globe filled with oxygen ; they are found to 
absorb that gas in proportion as they change in color. 
The chemical nature of this process is thus completely 
established. The diminution of the gas which occurs, 
can only be owing to the union of a large proportion of 
oxygen with those substances which are already in the 
state of oxides, or to the oxidation of the hydrogen, in 
those vegetable compounds which contain it in excess. 
The fallen brown or yellow leaves of the oak contain, 
no longer, tannin, and those of the poplar no balsamic 
constituents. 

The property which green leaves possess, of absorb- 
ing oxygen, belongs also to fresh wood, whether taken 
from a twig, or from the interior of the trunk of a tree. 
When fine chips of such wood are placed in a moist 
condition, under a jar filled with oxygen, the gas is seen 
to diminish in volume. But wood, dried by exposure 



82 OF THE ASSIMILATION OF CARBON. 

to the atmosphere and then moistened, converts the oxy- 
gen into carbonic acid, without change of vohime ; fresh 
wood, therefore, absorbs most oxygen. 

MM. Petersen and Schodler have shown, by tiie 
careful elementary analysis of 24 different kinds of wood, 
that they contain carbon and the elements of water, with 
the addition of a certain quantity of hydrogen. Oak 
wood, recently taken from the tree, and diied at 100^ 
C. (212° F.), contains 49.432 carbon, 6.069 hydrogen, 
and 44.499 oxygen. 

The proportion of hydrogen, which is necessary to 
combine with 44.498 oxygen in order to form water, is 
I of this quantity, namely 5.56 ; it is evident, therefore, 
that oak wood contains y\ more hydrogen than corre- 
sponds to this proportion. In Pinus Larix, P. Abies^ 
and P. Picea, ths excess of hydrogen amounts to i, and 
in Tilia Europcea to i. The quantity of hydrogen stands 
in some relation to the specific weight of the wood ; the 
lighter kinds of wood contain more of it than the heavier. 
In ebony wood (Diospyros Ebenum) the oxygen and 
hydrogen are in exactly the same proportion as in water. 

The difference between the composition of the varie- 
ties of wood, and that of simple woody fibre, depends, 
unquestionably, upon the presence of constituents, in 
part soluble, and in part insoluble, such as resin and 
other matters, which contain a large proportion of hydro- 
gen : the hydrogen of such substances being in the analy- 
sis of the various woods superadded to tiiat of the true 
woody fibre. 

It has previously been mentioned, that mouldering oak 
wood contains carbon and the elements of water without 
any excess of hydrogen. But the proportions of its 
constituents must, necessarily, have been different, if the 



INFLUENCE OF THE SHADE ON PLANTS. 83 

volume of the air had not changed during its decay, 
because the proportion of hydrogen in those component 
substances of the wood which contained it in excess is 
here diminished, and this diminution could only be effect- 
ed by an absorption of oxygen. 

Most vegetable physiologists have connected the emis- 
sion of carbonic acid during the night, with the absorp- 
tion of oxygen from the atmosphere, and have considered 
these actions as a true process of respiration in plants, 
similar to that of animals, and like it, having for its re- 
sult the separation of carbon from some of their con- 
stituents. This opinion has a very weak and unstable 
foundation. 

The carbonic acid, which has been absorbed by the 
leaves and by the roots, together with water, ceases to 
be decomposed on the departure of daylight ; it is dis- 
solved in the juices, which pervade all parts of the plant, 
and escapes every moment through the leaves, in quantity 
corresponding to that of the water, which evaporates. 

A soil, in which plants vegetate vigorously, contains a 
certain quantity of moisture, which is indispensably 
necessary to their existence. Carbonic acid, likewise, 
is always present in such a soil, whether it has been ab- 
stracted from the air, or has been generated by the decay 
of vegetable matter. Rain and well water, as well as 
that from other sources, invariably contain carbonic acid. 
Plants during their life constantly possess the power of 
absorbing by their roots moisture, and, along with it, air, 
and carbonic acid. Is it, therefore, surprising, that the 
carbonic acid should be returned, unchanged, to the at- 
mosphere, along with water, when light (the cause of the 
fixation of its carbon) is absent .'' 

Neither this emission of carbonic acid nor the absorp- 



84 OF THE ASSIMILATION OF CARBON. 

tion of oxygen has any connexion with the process of 
assimilation ; nor have they the slightest relation to one 
anotiier ; the one is a purely mechanical, the other a 
purely chemical process. A cotton wick, enclosed in a 
lamp, which contains a liquid saturated with carbonic 
acid, acts exactly in the same manner as a living plant in 
the night. Water and carbonic acid are sucked up by 
capillary attraction, and both evaporate from the exterior 
part of the wick. 

Plants, which live in a soil containing humus, exhale 
much more carbonic acid during the night than those 
which grow in dry situations ; they also yield more in 
rainy than in dry weather. These facts point out to us 
the cause of the numerous contradictory observations, 
which have been made with respect to the change im- 
pressed upon the air by living plants, both in darkness, 
and in common daylight, but which are unworthy of 
consideration, as they do not assist in the solution of the 
main question. 

There are other facts which prove in a decisive manner 
that plants yield more oxygen to the atmosphere than they 
extract from it ; these proofs, however, are to be drawn 
with certainty only from plants which live under water. 

When pools and ditches, the bottoms of which are 
covered with growing plants, freeze upon their surface in 
winter, so that the w^ater is completely excluded from the 
atmosphere, by a clear stratum of ice, small bubbles of 
gas are observed to escape, continually, during the day, 
from the points of the leaves and twigs. These bubbles 
are seen most distinctly when the rays of the sun fall 
upon the ice ; they are very small at first, but collect 
under the ice and form large bubbles. They consist of 
pure oxygen gas. Neither during the night, nor during 



NEGLECT OF CHEMISTRY BY BOTANISTS. 85 

the day when the sun does not shine, are they observed 
to diminish in quantity. The source of this oxygen is 
the carbonic acid dissolved in the water, which is absorb- 
ed by the plants, but is again supplied to the water, by 
the decay of vegetable substances contained in the soil. 
If these plants absorb oxygen during the night, it can be 
in no greater quantity than that which the surrounding 
water holds in solution, for the gas, which has been ex- 
haled, is not again absorbed. The action of water-plants 
cannot be supposed to form an exception to a great law 
of nature, and the less so, as the different action of aerial 
plants upon the atmosphere is very easily explained. 

The opinion is not new that the carbonic acid of the 
air serves for the nutriment of plants, and that its carbon 
is assimilated by them ; it has been admitted, defended, 
and argued for, by the soundest and most intelligent 
natural philosophers, namely, by Priestley, Sennehier, 
De Saussu7-e, and even by Ingenhouss himself. There 
scarcely exists a theory in natural science, in favor of 
which there are more clear and decisive arguments. 
How, then, are we to account for its not being received 
in its full extent by most other physiologists, for its 
being even disputed by many, and considered by a few 
as quite refuted ? 

All this is due to two causes, which we shall now 
consider. 

One is, that in botany the talent and labor of in- 
quirers has been wholly spent in the examination of 
form and structure : -chemistry and physics have not 
been allowed to sit in council upon the explanation of 
the most simple processes ; their experience and their 
laws have not been employed, though the most powerful 
means of help in the acquirement of true knowledge. 



86 OF THE ASSIMILATION OF CABBON. 

They have not been used, because their study has been 
neglected. 

All discoveries in physics and in chemistry, all ex- 
planations of chemists, must remain without fruit and 
useless, because, even to the great leaders in physiology, 
carbonic acid, ammonia, acids, and bases, are sounds 
without meaning, words without sense, terms of an un- 
known language, which awaken no thoughts and no 
associations. They treat these sciences like the vulgar, 
who despise a foreign literature in exact proportion to 
their ignorance of it ; since even when they have had 
some acquaintance with them, they have not understood 
their spirit and application. 

Physiologists reject the aid of chemistry in their 
inquiry into the secrets of vitality, although it alone 
could guide them in the true path ; they reject chem- 
istry, because, in its pursuit of knowledge, it destroys 
the subjects of its investigation ; but they forget that 
the knife of the anatomist must dismember the body, 
and destroy its organs, if an account is to be given of 
their form, structure, and functions. 

When pure potato starch is dissolved in nitric acid, 
a ring of the finest wax remains. What can be opposed 
to the conclusion of the chemist, that each grain of 
starch consists of concentric layers of wax and amylum, 
which thus mutually protect each other against the 
action of water and ether ? Can results of this kind, 
which illustrate so completely both the nature and prop- 
erties of bodies, be attained by the microscope ? Is it 
possible to make the gluten in a piece of bread visible 
in all its connexions and ramifications ? It is impossible 
by means of instruments ; but if the piece of bread is 
placed in a lukewarm decoction of malt, the starch, and 



OBJECT OF EXPERIMENTS IN PHYSIOLOGY. 87 

the substance called dextrine,* are seen to dissolve like 
sugar in water, and, at last, nothing remains except the 
gluten, in the form of a spongy mass, the minute pores 
of which can be seen only by a microscope. 

Chemistry offers innumerable resources of this kind 
which are of the greatest use in an inquiry into the 
nature of the organs of plants, but they are not used, 
because the need of them is not felt. The most im- 
portant organs of animals and their functions are known, 
although they may not be visible to the naked eye. 
But, in vegetable physiology, a leaf is in every case 
regarded merely as a leaf, notwithstanding that leaves 
generating oil of turpentine or oil of lemons must pos- 
sess a different nature from those in which oxalic acid 
is formed. Vitality, in its peculiar operations, makes 
use of a special apparatus for each function of an organ. 
A rose twig engrafted upon a lemon-tree, does not 
bring forth lemons but roses. Vegetable physiologists 
in the study of their science have not directed their 
attention to that part of it which is most worthy of 
investigation. 

The second cause of the incredulity with which 
physiologists view the theory of the nutrition of plants 
by the carbonic acid of the atmosphere is, that the art 

* Raspail has shown that starch consists of small spherules, each 
of which has a coating less soluble than its interior; that heat bursts 
these and lets out their contents, which consist of a gum-like sub- 
stance, called by Biot dextrine, from its turning the plane of polariza- 
tion of light to the right hand. It is white, insipid, transparent in 
thin flakes, and gummy. At 280" F. it becomes brown and acquires 
the flavor of toasted bread. It is much employed by the French 
pastry cooks and confectioners ; being reduced to powder it may be 
introduced into all kinds of pastries, bread, chocolate, «&c. For its 
preparation &c., see Ure's Dictionary of Jlits and Manufactures, and 
Webster's Chemistry, 510. 



88 OF THE ASSIMILATION OF CARBON. 

of experimenting is not known in physiology, it being 
an art which can be learned accurately only in the 
chemical laboratory. Nature speaks to us in a peculiar 
language, in the language of phenomena ; she answers 
at all times the questions which are put to her ; and 
such questions are experiments. An experiment is the 
expression of a thought : we are near the truth when 
the phenomenon, elicited by the experiment, corre- 
sponds to the thought ; while the opposite result shows 
that the question was falsely stated, and that the con- 
ception was erroneous. 

The critical repetition of another's experiments must 
be viewed as a criticism of his opinions ; if the result 
of the criticism be merely negative, if it do not suggest 
more correct ideas in the place of those which it is 
intended to refute, it should be disregarded ; because 
the worse experimenter the critic is, the greater will be 
the discrepancy between the results he obtains and the 
views proposed by the other. 

It is too much forgotten by physiologists, that their 
duty really is not to refute the experiments of others, 
nor to show that they are erroneous, but to discover 
truth, and that alone. It is startling, when we reflect 
that all the time and energy of a multitude of persons 
of genius, talent, and knowledge, are expended in en- 
deavours to demonstrate each other's errors. 

The question whether carbonic acid is the food of 
plants or not, has been made the subject of experinients 
with perfect zeal and good faith ; the results have been 
opposed to that view. But how was the inquiry in- 
stituted ? 

The seeds of balsamines, beans, cresses, and gourds, 
were sown in pure Carrara marble, and sprinkled with 



CONDITIONS ESSENTIAL TO NUTRITION. 89 

water containing carbonic acid. The seeds sprang, but 
the plants did not attain to the developement of the third 
small leaf. In other cases, they allowed the water to 
penetrate the marble from below, yet, in spile of this, 
they died. It is worthy of observation, that they lived 
longer with pure distilled water than with that impreg- 
nated with carbonic acid ; but still, in this case also, 
they eventually perished. Other experimenters sowed 
seeds of plants in flowers of sulphur and sulphate of 
baryta, and tried to nourish them with carbonic acid, 
but without success. 

Such experiments have been considered as positive 
proofs, that carbonic acid will not nourish plants ; but 
the manner in which they were instituted is opposed to 
all rules of philosophical inquiry, and to all the laws 
of chemistry. 

Many conditions are necessary for the life of plants ; 
those of each genus require special conditions, and 
should but one of these be wanting, although all the 
rest be supplied, the plants will not be brought to 
maturity. The organs of a plant, as well as those of an 
animal, contain substances of the most different kinds ; 
some are formed solely of carbon and the elements 
of water, others contain nitrogen, and in all plants we 
find metallic oxides in the state of salts. The food 
which can serve for the production of all the organs 
of a plant, must necessarily contain all its elements. 
These most essential of all the chemical qualities of 
nutriment may be united in one substance, or they may 
exist separately in several ; in which case, the one con- 
tains what is wanting in the other. Dogs die although 
fed with jelly, a substance which contains nitrogen ; 
they cannot live upon white bread, sugar, or starch, 
8* 



90 OF THE ASSIMILATION OF CARBON. 

if these are given as food, to the exclusion of all other 
substances. Can it be concluded from this, that these 
substances contain no elements suited for assimilation .'' 
Certainly not. 

Vitality is the power which each organ possesses of 
constantly reproducing itself; /or this it requires a 
supply of substances which contain the constituent ele- 
ments of its own substance, and are capable of under- 
going transformation. All the organs together cannot 
generate a single element, carbon, nitrogen, or a mefal- 
lic oxide. 

When the quantity of the food is too great, or is not 
capable of undergoing the necessary transformation, or 
exerts any peculiar chemical action, the organ itself is 
subjected to a change : all poisons act in this manner. 
The most nutritious substances may cause death. In 
experiments such as those described above, every con- 
dition of nutrition should be considered. Besides those 
matters which form their principal constituent parts, 
both animals and plants require others, the peculiar 
functions of which are unknown. These are inorganic 
substances, such as common salt, the total want of 
which is in animals inevitably productive of death. 
Plants, for the same reason, cannot live unless supplied 
with certain metallic compounds. 

If we knew with certainty that there existed a sub- 
stance capable, alone, of nourishing a plant and of bring- 
ing it to maturity, we might be led to a knowledge of 
the conditions necessary to the life of all plants, by 
studying its characters and composition. If humus were 
such a substance, it would have precisely the same 
value as the only single food which nature has produced 
for animal organization, namely, milk (Prout). The 



CONDITIONS ESSENTIAL TO NUTRITION. 91 

constituents of milk, are cheese or caseine, a compound 
containing nitrogen in large proportion ; butter, in which 
hydrogen abounds, and sugar of milk, a substance with 
a large quantity of hydrogen and oxygen in the same 
proportion as in water. It also contains in solution, 
lactate of soda, phosphate of lime, and common salt ; 
and a peculiar aromatic product exists in the butter, 
called butric acid. The knowledge of the composition 
of milk is a key to the conditions necessary for the pur- 
poses of nutrition of all animals. 

All substances which are adequate to the nourishment 
of animals, contain those materials united, though not 
always in the same form ; nor can any one be wanting, 
for a certain space of time, without a marked effect on 
the health being produced. The employment of a sub- 
stance as food, presupposes a knowledge of its capacity 
of assimilation, and of the conditions under which this 
takes place. 

A carnivorous animal dies in the vacuum of an air- 
pump, even though supplied with a superabundance of 
food ; it dies in the air, if the demands of its stomach 
are not satisfied ; and it dies in pure oxygen gas, how- 
ever lavishly nourishment be given to it. Is it hence to 
be concluded, that neither flesh, nor air, nor oxygen, is« 
fitted to support life ? Certainly not. 

From the pedestal of the Trajan column at Rome, we 
might chisel out each single piece of stone, if, upon the 
extraction of the second, we replaced the first. But 
could we conclude from this, that the column was sus- 
pended in the air, and not supported by a single piece 
of its foundation .'' Assuredly not. Yet the strongest 
proof would have been given, that each portion of the 



92 OF THE ASSIMILATION OF CARBON. 

pedestal could be removed without the downfall of the 
column. 

Animal and vegetable physiologists, however, come 
to such conclusions with respect to the process of as- 
similation. They institute experiments without being 
acquainted with the circumstances necessary for the con- 
tinuance of life, — with the qualities and proper nutri- 
ment of the animal or plant on which they operate, — 
or with the nature and chemical constitution of its or- 
gans. These experiments are considered by them as 
convincing proofs, whilst they are fitted only to awaken 
pity. 

Is it possible to bring a plant to maturity by means of 
carbonic acid and water, without the aid of some sub- 
stance containing nitrogen, which is an essential constit- 
uent of the sap, and indispensable for its production ? 
Must the plant not die, however abundant the supply of 
carbonic acid may be, as soon as the first small leaves 
have exhausted the nitrogen contained in the seeds ? 

Can a plant be expected to grow in Carrara marble, 
even when an azotized substance is supplied to it, but 
when the marble is sprinkled with an aqueous solution 
of carbonic acid, which dissolves the lime and forms 
supercarbonate of lime .'' A plant of the family of the 
Plumbogine^, upon the leaves of which fine hornlike, or 
scaly processes of crystallized carbonate of lime are 
formed, might, perhaps, attain maturity under such cir- 
cumstances ; but these experiments alone are sufficient 
to prove, that cresses, gourds, and balsamines, cannot 
be nourished by supercarbonate of lime, in the absence 
of matter containing nitrogen. We may indeed con- 
clude, that the salt of lime acts as a poison, since the 



CONDITIONS ESSENTIAL TO NUTRITION. 93 

development of plants will advance further in pure 
water, when lime and carbonic acid are not used. 

Moist flowers of sulphur attract oxygen from the at- 
mosphere and become acid. Js it possible that a plant 
can grow and flourish in presence of free sulphuric acid, 
with no other nourishment than carbonic acid ? It is 
true, the quantity of sulphuric acid formed thus in hours, 
or in days, may be small, but the property of each par- 
ticle of the sulphur to absorb oxygen and retain it, is 
present every moment. 

When it is known that plants require moisture, car- 
bonic acid, and air, should we choose, as the soil for 
experiments on their growth, sulphate of barytes, which, 
from its nature and specific gravity, completely prevents 
the access of air ? 

All these experiments are valueless for the decision 
of any question. It is absurd to take for them any soil 
at mere hazard, as long as we are ignorant of the func- 
tions performed in plants by those inorganic substances 
which are apparently foreign to them. It is quite im- 
possible to mature a plant of the family of the Graminea, 
or of the Equisetacea, the solid framework of which 
contains silicate of potash, without silicic acid and pot- 
ash, or a plant of the genus Oxalis without potash, or 
saline plants such as the saltworts (Salsola and Salicor- 
7iia), without chloride of sodium, or at least some salt of 
similar properties. All seeds of the Gramlnece contain 
phosphate of magnesia ; the solid parts of the roots of 
the althcea contain more phosphate of lime than woody 
fibre. Are these substances merely accidentally pres- 
ent .'' A plant should not be chosen for experiment, 
when the matter which it requires for its assimilation is 
not well known. 



94 ON THE ASSIMILATION OF CARBON. 

What value now can be attached to experiments in 
which all those matters which a plant requires in the 
process of assimilation, besides its mere nutriment, have 
been excluded with the greatest care ? Can the laws of 
life be investigated in an organized being which is dis- 
eased or dying ? 

The mere observation of a wood or meadow is infi- 
nitely better adapted to decide so simple a question, 
than all the trivial experiments under a glass globe ; the 
only difference is, that instead of one plant there are 
thousands. When we are acquainted with the nature of 
a single cubic inch of their soil, and know the composi- 
tion of the air and rain-water, we are in possession of all 
the conditions necessary to their life. The source of the 
different elements entering into the composition of plants 
cannot possibly escape us, if we know in what form 
they take up their nourishment, and compare its com- 
position with that of the vegetable substances which 
compose their structure. 

All these questions will now be examined and dis- 
cussed. It has been already shown, that the carbon of 
plants is derived from the atmosphere : it still remains 
for us to inquire, what power is exerted on vegetation 
by the humus of the soil and the inorganic constituents 
of plants, and also to trace the sources of their nitro- 
gen. 



ORIGIN AND ACTION OF HUMUS. 95 



CHAPTER III. 

ON THE ORIGIN AND ACTION OF HUMUS. 

All plants and vegetable structures undergo two 
processes of decomposition after death. One of these 
is named fermentation^ the other decay , putrefaction, or 
eremacausis.* 

Decay is a slow process of combustion, a process, 
therefore, in which the combustible parts of a plant 
unite with the oxygen of the atmosphere. 

The decay of woody fibre (the principal constituent 
of all plants) is accompanied by a phenomenon of a pe- 
culiar kind. This substance, in contact with air or ox- 
ygen gas, converts the latter into an equal volume of 
carbonic acid, and its decay ceases upon the disappear- 



* The word eremacausis was proposed by the author some time 
since, in order to explain the true nature of putrefaction ; it is com- 
pounded from fi^ifia, slow, and xaZfis, combustion. — Tr. 

Eremacausis is the art of gradual combination of the combustible 
elements of a body wilh the oxygen of the air; a slow combustion or 
oxidation. 

The conversion of wood into humus, the formation of acetic acid 
out of alcohol, nitrification, and numerous other processes, are of this 
nature. Vegetable juices of every kind, parts of animal and vegetable 
substances, moist sawdust, blood, &c., cannot be exposed to the air, 
without suffering immediately a progressive change of color and prop- 
erties, during which oxygen is absorbed. These changes do not take 
place when water is excluded, or when the substances are exposed to 
the temperature of 32°, and diffeient bodies require different degrees 
of heat, in order to effect the absorption of oxygen, and, consequently, 
their eremacausis. The property of suffering this change is possessed 
in the highest degree by substances which contain nitrogen. Liebig. 
Org. Chcm. Part 2d. 



96 ORIGIN AND ACTION OF HUMUS. 

ance of the oxygen. If the carbonic acid is removed, 
and oxygen replaced, its decay recomnaences, that is, it 
again converts oxygen into carbonic acid. Woody fibre 
consists of carbon and the elements of water ; and if 
we judge only from the products formed during its de- 
composition, and from those formed by pure charcoal, 
burned at a high temperature, we might conclude that 
the causes were the same in both : the decay of woody 
fibre proceeds, therefore, as if no hydrogen or oxygen 
entered into its composition.* 

A very long time is required for the completion of 
this process of combustion, and the presence of water 
is necessary for its maintenance : alkalies promote it, 
but acids retard it ; all antiseptic substances, such as 
sulphurous acid, the mercurial salts, empyreumatic oils, 
&c., cause its complete cessation. 

Woody fibre, in a state of decay, is the substance 
called humus. \ 

* In the appendix to the Third Report of the Mgriculture of Massa- 
chusetts, 1840, Dr. S. L. Dana adduces the following example, to show 
that even a moist plant will not decay, if air is excluded. A piece of 
a while birch tree was taken from a depth of twenty-five feet below 
the surface, in Jjowell. " It must have been inhuirred there prob- 
ably before the creation of man, yet this most perishable of all wood 
is nearly as sound as if cut from the forest last fall." 

t The humic acid of chemists is a product of the decomposition of 
humus by alkalies ; it does not exist in the humus of vegetable physi- 
ologists, — L. 

The product of the decay of vegetable matters has usually been 
called vegetable mould, a term which Dr. Jackson prefers to retain. 
This mould he finds highly charged with carbonic acid, and also to 
contain man}' other acids. The decay of wood produces similar re- 
sults. 



VEGETABLE MOULD. 97 



VEGETABLE MOULD. 



The term vegetable mould, in its general signification, 
is applied to a mixture of disintegrated minerals, with 
the remains of animal and vegetable substances. It may 
be considered as earth in which humus is contained in a 
state of decou)position. lis action upon the air has 
been fully investigated by Ingenhouss and De Saussure. 

When moist vegetable mould is placed in a vessel full 
of air, it extracts the oxygen therefrom with greater 
rapidity than decayed wood, and replaces it by an equal 
volume of carbonic acid. When this carbonic acid is 
removed and fresh air admitted, the same action is re- 
peated. 

Cold water dissolves only to.Ioo^J^ of its own weight 
of vegetable mould ; and the residue left on its evapora- 
tion consists of common salt with traces of sulphate of 
potash and lime, and a minute quantity of organic matter, 
for it is blackened when heated to redness. Boiling 
water extracts several substances from vegetable mould, 
and acquires a yellow or yellowish brown color, which is 
dissipated by absorption of oxygen from the air, a black 
flocculent deposit being formed. When the colored so- 
lution is evaporated, a residue is left which becomes 
black on being heated to redness, and afterwards yields 
carbonate of potash when treated with water. 

A solution of caustic potash becomes black when 
placed in contact with vegetable mould, and the addition 
of acetic acid to the colored solution causes no precipi- 
tate or turbidity. But dilute sulphuric acid throws down 

* From the Second Part of the original work. 

9 



98 DECAY OP WOODY FIBRE. 

a light flocculent precipitate of a brown or black color, 
from which the acid can be removed with difficulty by 
means of water. When this precipitate, after having 
been washed with water, is brought whilst still moist 
under a receiver filled with oxygen, the gas is absorbed 
with great rapidity ; and the same thing takes place when 
the precipitate is dried in the air. In the perfectly dry 
state it has entirely lost its solubility in water, and even 
alkalies dissolve only traces of it. 

It is evident, therefore, that boiling water extracts a 
matter from vegetable mould, which owes its solubility to 
the presence of the alkaline salts contained in the remains 
of plants. This substance is a product of the incom- 
plete decay of woody fibre. Its composition is interme- 
diate between woody fibre and humus into which it is 
converted, by being exposed in a moist condition to the 
action of the air. 

The conversion of woody fibre into the substances 
termed humus and mould is, on account of its influence 
on vegetation, one of the most remarkable processes of 
decomposition which occur in nature. 

Decay is not less important in another point of view ; 
for, by means of its influence on dead vegetable matter, 
the oxygen which plants retained during life is again re- 
stored to the atmosphere. 

The decomposition of woody fibre is effected in three 
forms, the results of which are diflerent, so that it is 
necessary to consider each separately. 

The first takes place when it is in the moist condition, 
and subject to free, uninterrupted access of air ; the 
second occurs when air is excluded ; and the third when 
the wood is covered with water, and in contact with pu- 
trefying organic matter. 



ITS COMPOSITION. 99 

It is known that woody fibre may be kept under 
water, or in dry air, for thousands of years without suf- 
fering any appreciable change ; but that when brought 
into contact with air in the moist condition, it converts 
the oxygen surrounding it into the same volume of car- 
bonic acid, and is itself gradually changed into a yellow- 
ish brown, or black matter, of a loose texture. 

According to the experiments of De Saussure, 240 
parts of dry sawdust of oak wood convert 10 cubic in- 
ches of oxygen into the same quantity of carbonic acid, 
which contains 3 parts, by weight, of carbon ; while 
the weight of the sawdust is diminished by 15 parts. 
Hence 12 parts by weight, of water, are at the same 
time separated from the elements of the wood. 

It has already been mentioned, that pure woody fibre 
contains carbon and the elements of water. Humus, 
however, is not produced by the decay of pure woody 
fibre, but by that of wood which contains foreign soluble 
and insoluble organic substances, besides its essential 
constituent. 

The relative proportion of the component elements 
is, on this account, different in oak wood and in beech, 
and the composition of both of these differs very much 
from woody fibre, which is the same in all vegetables. 
The difference, however, is so trivial, that it may be al- 
together neglected in the consideration of the questions 
which will now be brought under discussion ; besides, 
the quantity of the foreign substances is not constant, 
but varies according to the season of the year. 

According to the careful analysis of Gay-Lussac and 
Thcnard, 100 parts of oak wood, dried at 212^^ (100^ 
C), from which all soluble substances had been ex- 
tracted by means of water and alcohol, contained 52.53 



100 DECAY OF WOODY FIBRE. 

parts of carbon, and 47.47 parts of hydrogen and oxy- 
gen, in the same proportion as they are contained in 
water. 

Now it has been mentioned that moist wood acts in 
oxygen gas exactly as if its carbon combined directly 
with oxygen, and the products of this action are car- 
bonic acid and humus. 

If the action of the oxygen were confined to the car- 
bon of the wood, and if nothing but carbon were re- 
moved from it, the remaining elements would necessarily 
be found in the humus, unchanged except in the partic- 
ular of being combined with less carbon. The final 
result of the action would therefore be a complete dis- 
appearance of the carbon, whilst nothing but the ele- 
ments of water would remain. 

But when decaying wood is subjected to examination 
in different stages of its decay, the remarkable result is 
obtained, that the proportion of carbon in the different 
products augments. Consequently, if we did not take 
into consideration the evolution of carbonic acid under 
the influence of the air, the conversion of wood into 
humus might be viewed as a removal of the elements of 
water from the carbon. 

The analysis of mouldered oak wood, which was 
taken from the interior of the trunk of an oak, and pos- 
sessed a chocolate brown color and the structure of 
wood, showed that 100 parts of it contained 53.36 parts 
of carbon, and 46.44 parts of hydrogen and oxygen in 
the same relative proportions as in water. From an 
examination of mouldered wood of a light brown color, 
easily reducible to a fine powder, and taken from an- 
other oak, it appeared that it contained 56.211 carbon 
and 43.789 water. 



TIME REQUIRED. 101 

These indisputable facts point out the similarity of 
the decay of wood, with the slow combustion or oxida- 
tion of bodies which contain a large quantity of hydro- 
gen. Viewed as a kind of combustion, it would indeed 
be a very extraordinary process, if the carbon combined 
directly with the oxygen ; for it would be a combustion 
in which the carbon of the burning body augmented 
constantly, instead of diminishing. Hence it is evident 
that it is the hydrogen which is oxidized at the expense 
of the oxygen of the air ; while the carbonic acid is 
formed from the elements of the wood. Carbon never 
combines at common temperatures with oxygen, so as 
to form carbonic acid. 

In whatever stage of decay wood may be, its elements 
must always be capable of being represented by their 
equivalent numbers. 

The following formula illustrates this fact with great 
clearness : 

C36 H22 022, — oak wood, according to Gay-Lussac and Thenard* 
C35 H20 O20, — humus from oak wood (Meyer) A 
C34H18 018,— " " {Dr.WiWj.X 

Tt is evident from these numbers that for every two 
equivalents of hydrogen which is oxidized, two atoms of 
oxygen and one of carbon are set free. 

Under ordinary circumstances, woody fibre requires 
a very long time for its decay ; but this process is of 
course much accelerated by an elevated temperature and 
free unrestrained access of air. The decay, on the 
contrary, is much retarded by absence of moisture, and 

* The calculation gives 52.5 carbon, and 47.5 water, 
t The calculation gives 54 carbon and 46 water. 
X The calculation gives 56 carbon and 44 water. 
9* 



102 DECAY OF WOODY FIBRE. 

by the wood being surrounded with an atmosphere of 
carbonic acid, which prevents the access of air to the 
decaying matters. 

Sulphurous acid, and all antiseptic substances, arrest 
the decay of woody fibre. It is well known that corro- 
sive sublimate is employed for the purpose of protecting 
the timber of ships from decay ; it is a substance which 
completely deprives vegetable or animal matters, the 
most prone to decomposition, of their property of en- 
tering into fermentation, putrefaction, or decay. 

But the decay of woody fibre is very much accelerat- 
ed by contact with alkalies or alkaline earths ; for these 
enable substances to absorb oxygen, which do not pos- 
sess this power themselves ; alcohol, gallic acid, tannin, 
the vegetable coloring matters and several other sub- 
stances, are thus affected by them. Acids produce quite 
an opposite effect ; they greatly retard decay. 

Heavy soils, consisting of loam, retain longest the 
most important condition for the decay of the vegetable 
matter contained in it, viz. water ; but their impermea- 
ble nature prevents contact with the air. 

In moist sandy soils, particularly such as are compos- 
ed of a mixture of sand and carbonate of lime, decay 
proceeds very quickly, it being aided by the presence 
of the slightly alkaline lime. 

Now let us consider the decay of woody fibre during 
a very long period of time, and suppose that its cause is 
the gradual removal of the hydrogen in the form of 
water, and the separation of its oxygen in that of car- 
bonic acid. It is evident that if we subtract from the 
formula C36, H22, 022, the 22 equivalents of oxygen, 
with 11 equivalents of carbon, and 22 equivalents of hy- 
drogen, which are supposed to be oxidized by the oxy- 



DECAY OF WOODY FIBRE. 103 

gen of the air, and separated in the form of water ; then 
from 1 atom of oak wood, 25 atoms of pure carbon will 
remain as the final product of the decay. In other 
words, 100 parts of oak, which contain 52.5 parts of 
carbon, will leave as a residue 37 parts of carbon which 
must remain unchanged, since carbon does not combine 
with oxygen at common temperatures. 

But this final result is never attained in the decay of 
wood under common circumstances ; and for this rea- 
son, that with the increase of the proportion of carbon 
in the residual humus, as in all decompositions of this 
kind, its attraction for the hydrogen, which still remains 
in combination, also increases, until at length the affinity 
of oxygen for the hydrogen is equalled, by that of the 
carbon for the same element. 

In proportion as the decay of woody fibre advances, 
its property of burning with flame, or in other words, 
of developing carburetted hydrogen on the application 
of heat, diminishes. Decayed wood burns without 
flame ; whence no other conclusion can be drawn, than 
that the hydrogen, which analysis shows to be present, 
is not contained in it in the same form as in wood. 

Decayed oak contains more carbon than fresh wood, 
but its hydrogen and oxygen are in the same proportion. 

We would naturally expect that the flame given out 
by decayed wood should be more brilliant, in proportion 
to the increase of its cprbon, but we find, on the con- 
trary, that it burns like tinder, exactly as if no hydrogen 
were present. For the purposes of fuel, decayed or 
diseased wood is of little value, for it does not possess 
the property of burning with flame, a property upon 
which the advantages of common wood depend. The 
hydrogen of decayed wood must consequently be sup- 



104 DECAY OF WOODY FIBRE. 

posed to be in the state of water ; for had it any other 
form, the characters we have described would not be 
possessed by the decayed wood. 

If we suppose decay to proceed in a liquid, which 
contains both carbon and hydrogen, then a compound 
containing still more carbon must be formed, in a man- 
ner similar to the production of the crystalline colorless 
napthalin from a gaseous compound of carbon and hy- 
drogen. And if the compound thus formed were itself 
to undergo further decay, the final result must be the 
separation of carbon in a crystalline form. 

Science can point to no process capable of account- 
ing for the origin and formation of diamonds, except the 
process of decay. Diamonds cannot be produced by 
the action of fire, for a high temperature, and the pres- 
ence of oxygen gas, would call into play their combusti- 
bility. But there is the greatest reason to believe that 
they are formed in the humid way, that is, in a liquid, 
and the process of decay is the only cause to which their 
formation can with probability be ascribed. 

Amber, fossil resin, and the acids in mellite, are the 
products of vegetable matter which has suffered decom- 
position. They are found in wood or brown coal, and 
have evidently proceeded from the decomposition of sub- 
stances which were contained in quite a different form in 
the living plants. They are all distinguished by the pro- 
portionally small quantity of hydrogen which they con- 
tain. The acid from the mellite (mellitic acid) con- 
tains precisely the same proportions of carbon and oxygen 
as that from amber (succinic acid) ; they differ only in 
the proportion of their hydrogen. M. Bromeis* found 

* Liebig's Jinnalen, Band xxxiv., Heft 3. 



HUMUS EVOLVES CARBONIC ACID. 105 

that succinic acid might be artificially foi'tned by the ac- 
tion of nitric acid on stearic acid, a true process of ere- 
macausis ; the experiment was made in this laboratory 
(Giessen) . 

The property of woody fibre to convert surrounding 
oxygen gas into carbonic acid diminishes in pioportion as 
its decay advances, and at last a certain quantity of a 
brown coaly-looking substance remains, in which this 
property is entirely wanting. This substance is called 
mould ; it is the product of the complete decay of woody 
fibre. Mould constitutes the principal part of all the 
strata of brown coal and peat. 



Humus acts in the same manner in a soil permeable to 
air as in the air itself ; it is a continued source of car- 
bonic acid, which it emits very slowly. An atmosphere 
of carbonic acid, foimed at the expense of the oxygen 
of the air, surrounds every particle of decaying humus. 
The cultivation of land, by tilling and loosening the soil, 
causes a free and unobstructed access of air. An atmo- 
sphere of carbonic acid is, therefore, contained in every 
fertile soil, and is the first and most important food for 
the young plants which grow in it. 

In spring, when those organs of plants are absent, 
which nature has appointed for the assumption of nour- 
ishment from the atmosphere, the component substance 
of the seeds is exclusively employed in the formation of 
the roots. Each new radicle fibril which a plant acquires 
may be regarded as constituting at the same time a mouth, 
a lung, and a stomach. The roots perform the functions 



106 ORIGIN AND ACTION OF HUMUS. 

of the leaves from the first moment of their formation ; 
they extract from the soil their proper nutriment, namely, 
the carbonic acid generated by the humus. 

By loosening the soil which surrounds young plants, 
we favor the access of air, and the formation of carbonic 
acid ; and on the other hand the quantity of their food is 
diminished by every difficulty which opposes the renewal 
of air. A plant itself effects this change of air at a cer- 
tain period of its growth. The carbonic acid, which 
protects the undecayed humus from further change, is 
absorbed and taken away by the fine fibres of the roots, 
and by the roots themselves ; this is replaced by atmo- 
spheric air, by which process the decay is renewed, and 
a fresh portion of carbonic acid formed. A plant at 
this time receives its food, both by the roots, and by the 
organs above ground, and advances rapidly to maturity. 

When a plant is quite matured, and when the organs, 
by which it obtains food from the atmosphere, are formed, 
the carbonic acid of the soil is no further required. 

Deficiency of moisture in the soil, or its complete 
dryness, does not now check the growth of a plant, pro- 
vided it receives from the dew and the atmosphere as 
much as is requisite for the process of assimilation. 
During the heat of summer it derives its carbon exclu- 
sively from the atmosphere. 

We do not know what height and strength nature has 
allotted to plants ; we are acquainted only with the size 
which they usually attain. Oaks are shown, both in 
London and Amsterdam, as remarkable curiosities, which 
have been reared by Chinese gardeners, and are only one 
foot and a half in height, although their trunks, barks, 
leaves, branches, and whole habitus, evince a venerable 



GROWTH OF PLANTS. 107 

age. The small turnip, grown at Teltow,* when placed 
in a soil which yields as much nourishment as it can take 
up, increases to several pounds in weight. 

The size of a plant is proportional to the surface of 
the organs xchich are destined to convey food to it. A 
plant gains another mouth and stomach with every new 
fibre of root, and every new leaf. 

The power which roots possess of taking up nourish- 
ment does not cease as long as nutriment is present. 
When the food of a plant is in greater quantity than its 
organs require for their own perfect development, the 
superfluous nutriment is not returned to the soil, but is 
employed in the formation of new organs. At the side 
of a cell, already formed, another cell arises ; at the side 
of a twig and leaf, a new twig and a new leaf are devel- 
oped. These new parts could not have been formed 
had there not been an excess of nourishment. The 
sugar and mucilage produced in the seeds, form the nu- 
triment of the young plants, and disappear during the de- 
velopment of the buds, green sprouts, and leaves. 
. . The power of absorbing nutriment from the atmo- 
sphere, with which the leaves of plants are endowed, 
being proportionate to the extent of their surface, every 
increase in the size and number of these parts is neces- 
sarily attended with an increase of nutritive power, and 
a consequent further development of new leaves and 
branches. Leaves, twigs, and branches, when com- 
pletely matured, as they do not become larger, do not 
need food for their support. For their existence as or- 
gans, they require only the means necessary for the per- 

* Teltow is a village near Berlin, where small turnips are cultivated 
in a sandy soil ; thej are much esteemed, and weigh rarely above one 
ounce. 



108 TRANSFORMATION OF ORGANIC SUBSTANCES. 

formaiice of the special functions to which they are des- 
tined by nature ; they do not exist on their own account. 

We know that the functions of the leaves and other 
green parts of plants are to absorb carbonic acid, and 
with the aid of light and moisture, to appropriate its car- 
bon. These processes are continually in operation ; 
they commence with the first formation of the leaves, 
and do not cease with their perfect development. But 
the new products arising from this continued assimilation, 
are no longer employed by the perfect leaves in their own 
increase : they serve for the formation of woody fibre, 
and all the solid matters of similar composition. The 
leaves now produce sugar, amylin or starch, and acids, 
which were previously formed by the roots when they 
were necessary for the development of the stem, buds, 
leaves and branches of the plant. 

The organs of assimilation, at this period of their 
life, receive more nourishment from the atmosphere 
than they employ in their own sustenance, and when 
the formation of the woody substance has advanced to 
a certain extent, the expenditure of the nutriment, the 
supply of which still remains the same, takes a new 
direction, and blossoms are produced. The functions 
of the leaves of most plants cease upon the ripening of 
their fruit, because the products of their action are no 
longer needed. They now yield to the chemical influ- 
ence of the oxygen of the air, generally suffer there- 
from a change in color, and fall off. 

A peculiar " transformation " of the matters con- 
tained in all plants takes place in the period between 
blossoming and the ripening of the fruit ; new com- 
pounds are produced, which furnish constituents of the 
blossoms, fruit, and seed. An organic chemical " trans- 



TRANSFORMATION OF ORGANIC SUBSTANCES. 109 

formation " is the separation of the elements of one or 
several combinations, and their reunion into two or 
several others, which contain the same number of ele- 
ments, either grouped in another manner, or in different 
proportions. Of two compounds formed in conse- 
quence of such a change, one remains as a component 
part of the blossom or fruit, while the other is separated 
by the roots in the form of excrementitious matter. 
No process of nutrition can be conceived to subsist in 
animals or vegetables, without a separation of effete 
matters. We know, indeed, that an organized body 
cannot generate substances, but can only change the 
mode of their combination, and that its sustenance and 
reproduction depend upon the chemical transformation! 
of the matters which are employed as its nutriment, and 
which contain its own constituent elements. 

Whatever we regard as the cause of these transforma- 
tions, whether the Vital Principle, Increase of Tem- 
perature, Light, Galvanism, or any other influence, the. 
act of transformation is a purely chemical process.. 
Combination and Decomposition can take place only 
when the elements are disposed to these changes. That 
which chemists name affinity indicates only the degree 
in which they possess this disposition. It will be 
shown, when considering the processes of fermentation 
and putrefaction, that every disturbance of the mutual 
attraction subsisting between the elements of a body 
gives rise to a transformation. The elements arrange 
themselves according to the degrees of their reciprocal 
attraction into new combinations, which are incapable 
of further change, under the same conditions. 

The products of these transformations vary with 
their causes, that is, with the different conditions on 
10 



110 ORIGIN AND ACTION OF HUMUS. 

which their production depended ; and are as innumera- 
ble as these conditions themselves. The chemical 
character of an acid, for example, is its unceasing dis- 
position to saturation by means of a base ;* this dispo- 
sition differs in intensity in different acids ; but when it 
is satisfied, the acid character entirely disappears. The 
chemical character of a base is exactly the reverse of 
this, but both an acid and a base, notwithstanding the 
great difference in their properties, effect, in most 
cases, the same kind of transformations. 

Hydrocyanic acid (prussic acid) f and water contain 

* Liebig applies the term base to compounds which unite with acids 
and neutralize their characters. The j>roduct is a salt. When the 
characters of both acids and bases disappear the compound is neutral. 

Some acids contain oxygen, others hydrogen. Several metals form 
acids with oxygen ; but the greater number of metallic oxides, are, 
in their relations, totally different from the acids. They form com- 
pounds, which, for the most part, are insoluble in water ; those soluble 
in water have an alkaline taste, and possess the property of restoring 
the blue color of vegetables, which have been reddened by acids. 
These also change many vegetable yellows to red or brown. The 
alkalies are soluble bases. Many salts redden vegetable blues, and 
others again restore the blue color of vegetables reddened by acids; 
:n the first instance, the salt possesses an acid ; and in the latter an 
alkaline reaction. 

A simple body which is capable of forming either an acid or a base, 
is termed a radical ; a compound radical consists of two or three sim- 
ple radicals, and comports itself in a similar manner to the simple 
radicals ; that is, it is capable of forming acids and bases. 

t Cyanogen is considered by Liebig as a compound base, and as 
such uniting with oxygen, hydrogen, and most other nonmetallic 
elements and with the metals. Cyanogen gas, or bicarburet of nitro- 
gen, is a compound of nitrogen and carbon, and was named from its 
affording a blue color and being an ingredient of Prussian blue. For 
the method of obtaining it, &c., see Webster's Chemistry, 3d edition, 
p. 219. 

With hydrogen it constitutes hydrocyanic acid. 



NATURE OF ORGANIC CHEMICAL PROCESSES. Ill 

the elements of carbonic acid, ammonia, urea, cyanuric 
acid, cyanilic acid, oxalic acid, formic acid, melam, 
ammelin, melamin, azulmin, mellon, hydromellonic acid, 
allantoin, &c. It is well known, that all these very 
different substances can be obtained from hydrocyanic 
acid and the elements of water, by various chemical 
transformations. 

The whole process of nutrition may be understood 
by the consideration of one of these transformations. 

Hydrocyanic acid and water, for example, when 
brought into contact with muriatic acid, are decom- 
posed into formic acid * and ammonia ; both of these 
products of decomposition contain the elements of hy- 
drocyanic acid and water, although in another form, 
and arranged in a different order. The change results 
from the strong disposition or struggle of muriatic acid 
to undergo saturation, in consequence of which the hy- 
drocyanic acid and water suffer mutual decomposition. 
The nitrogen of the hydrocyanic acid and the hydrogen 
of the water unite together and form a base, ammonia, 
with which the acid unites ; the chemical characters of 
the acid being at the same time lost, because its desire 
for saturation is satisfied by its uniting with ammonia. 
Ammonia itself was not previously present, but only its 
elements, and the power to form it. The simultaneous 
decomposition of hydrocyanic acid and water in this 
instance does not take place in consequence of the 
chemical affinity of muriatic acid for ammonia, since 
hydrocyanic acid and water contain no ammonia. An 
affinity of one body for a second, which does not exist, 
is quite inconceivable. The ammonia, in this case, is 



* An acid obtained from ants, hence its name. It is now obtained 

from sugar and other vegetable substances. 



112 ORIGIN AND ACTION OF HUMUS. 

formed only on account of the existing attractive desire 
of the acid for saturation. Hence we may perceive 
how much these modes of decomposition, to which the 
name of transformations or metamorphoses has been 
especially applied, differ from the ordinary chemical 
decompositions. 

In consequence of the formation of ammonia, the 
other elements of hydrocyanic acid, namely, carbon and 
hydrogen, unite with the oxygen of the decomposed 
water, and form formic acid, the elements of this sub- 
stance with the power of combination being present. 
Formic acid, here, represents the excrementitious mat- 
ters ; ammonia, the new substance, assimilated by an 
organ of a plant or animal. 

Each organ extracts from the food presented to it, 
what it requires for its own sustenance ; while the re- 
maining elements, which are not assimilated, combine 
together and are separated as excrement. The excre- 
mentitious matters of one organ come in contact with 
another during their passage through the organism, and 
in consequence suffer new transformations ; the useless 
matters rejected by one organ containing the elements 
for the nutrition of a second and a third organ ; but at 
last, being capable of no further transformations, they 
are separated from the system by the organs destined 
for that purpose. Each part of an organized being is 
fitted for its peculiar functions. A cubic inch of sul- 
phuretted hydrogen introduced into the lungs, would 
cause instant death, but it is formed, under a variety of 
circumstances, in the intestinal canal without any inju- 
rious effect.* 



* The danger of breathing carbonic acid gas is well known, but 
large quantities can be taken into the stomach with impunity and 
even benefit. 



ORGANIC CHEMICAL PROCESSES. 113 

In consequence of such transformations as we have 
described, excrements are formed of various composi- 
tion ; some of these contain carbon, in excess ; others 
nitrogen, and others again hydrogen and oxygen. The 
kidneys, Hver, and lungs, are organs of excretion ; the 
first separate from the body all those substances in 
which a large proportion of nitrogen is contained ; the 
second, those with an excess of carbon ; and the third, 
such as are composed principally of oxygen and hydro- 
gen. Alcohol, also, and the volatile oils which are in- 
capable of being assimilated, are exhaled through the 
lungs, and not through the skin. 

Respiration must be regarded as a slow process of 
combustion or constant decomposition. If it be subject 
to the laws which regulate the processes of decomposi- 
tion generally, the oxygen of the inspired air cannot 
combine directly with the carbon of compounds of that 
element contained in the blood ; the hydrogen only can 
combine with the oxygen of the air, or undergo a higher 
degree of oxidation. Oxygen is absorbed without unit- 
ing with carbon ; and carbonic acid is disengaged, the 
carbon and oxygen of which must be derived from mat- 
ters previously existing in the blood. 

All superabundant nitrogen is eliminated from the 
body, as a liquid excrement, through the urinary pas- 
sages ; all solid substances, incapable of further trans- 
formation, pass out by the intestinal canal, and all gase- 
ous matters by the lungs. 

We should not permit ourselves to be withheld, by 
the idea of a vital principle, from considering, in a 
chemical point of view, the process of the transformation 
of the food, and its assimilation by the various organs. 
This is the more necessary, as the views, hitherto held, 
10* 



114 ORIGIN AND ACTION OF HUMUS. 

have produced no results, and are quite incapable of 
useful application. 

Is it truly vitality, which generates sugar in the germ 
for the nutrition of young plants, or which gives to the 
stomach the power to dissolve, and to prepare for as- 
similation all the matter introduced into it ? A decoc- 
tion of malt possesses as little power to reproduce itself, 
as the stomach of a dead calf ; both are, unquestionably, 
destitute of life. But when amylin or starch is intro- 
duced into a decoction of malt, it changes, first into a 
gummy-like matter, and lastly into sugar. Hard boiled 
albumen, and muscular fibre can be dissolved in a de- 
coction of a calf's stomach, to which a few drops of 
muriatic acid have been added, precisely as in the stom- 
ach itself.* (Schwann, Schulz.) 

The power, therefore, to effect transformations, does 
not belong to the vital principle ; each transformation is 
owing to a disturbance in the attraction of the elements 
of a compound, and is consequently a purely chemical 
process. There is no doubt, that this process takes 
place in another form, from that of the ordinary decom- 
position of salts, oxides, or sulphurets. But is it the 
fault of chemistry, that physiology has hitherto taken no 
notice of this new form of chemical action .'' 

Physicians are accustomed to administer whole ounces 
of borax to patients suffering under urinary calculi, when 
it is known, that the bases of all alkaline salts, formed by 
organic acids, are carried through the urinary passages 
in the form of alkaline carbonates capable of dissolving 

* This remarkable action has been completely confirmed in this 
laboratory (Giessen), by Dr. Vogel, a highly distinguished young 
physiologist. — L. 



VITAL PRINCIPLE. 115 

calculi (Wohler). Is this rational? The medical re- 
ports state, that upon the Rhine, where so much cream 
of tartar is consumed in wine, the only cases of calcu- 
lous disorders are those which are imported from other 
districts. We know that the uric acid calculus is 
transformed into the mulberry calculus, (which contains 
oxalic acid,) when patients suffering under the former 
exchange the town, for the country, where less animal 
and more vegetable food is used. Are all these circum- 
stances incapable of explanation ? 

The volatile oil of the roots of valerian may be ob- 
tained from the oil generated during the fermentation of 
potatoes (Dumas), and the oil of the Spircea uhnoria 
from the crystalline matter of the bark of the willow 
(Piria). We are able to form in our laboratories, 
formic acid, oxalic acid, urea, and the crystalline sub- 
stances existing in the liquid of the allantois of the cow, 
all products, it is said, of the vital principle. We see, 
therefore, that this mysterious principle has many rela- 
tions in common with chemical forces, and that the 
latter can indeed replace it. What these relations 
are, it remains for physiologists to investigate. Truly, 
it would be extraordinary, if this vital principle, which 
uses every thing for its own purposes, had allotted no 
share to chemical forces, which stand so freely at its 
disposal. We shall obtain that which is attainable in a 
rational inquiry into nature, if we separate the actions 
belonging to chemical powers, from those which are 
subordinate to other influences. But the expression, 
" vital principle," must, in the mean time, be consider- 
ed as of equal value with the terms specific or dynamic 
in medicine : every thing is specific which we cannot 



116 ORIGIN AND ACTION OF HUMUS. 

explain, and dynamic is the explanation of all which we 
do not understand. 

Transformations of existing compounds are constant- 
ly taking place during the whole life of a plant, in conse- 
quence of which, and as the results of these trans-* 
formations, there are produced gaseous matters which 
are excreted by the leaves and blossoms, solid excre- 
ments deposited in the bark, and fluid soluble substances 
which are eliminated by the roots. Such secretions are 
most abundant immediately before the formation and 
during the continuance of the blossoms ; they diminish 
after the development of the fruit. Substances, con- 
taining a large proportion of carbon, are excreted by the 
roots and absorbed by the soil. Through the expulsion 
of these matters unfitted for nutrition, therefore, the soil 
receives again the greatest part of the carbon, which it 
had at first yielded to the young plants as food, in the 
form of carbonic acid. 

The soluble matter, thus acquired by the soil, is still 
capable of decay and putrefaction, and by undergoing 
these processes furnishes renewed sources of nutrition 
to another generation of plants ; it becomes humus. 
The leaves of trees, which fall in the forest in autumn, 
and the old roots of grass in the meadow, are likewise 
converted into humus by the same influence : a soil re- 
ceives more carbon in this form, than its decaying hu- 
mus had lost as carbonic acid. 

Plants do not exhaust the carbon of a soil, in the nor- 
mal condition of their growth ; on the contrary, they 
add to its quantity. But if it is true that plants give back 
more carbon to a soil than they take from it, it is evi- 
dent that their growth must depend upon the reception 
of nourishment from the atmosphere. The influence of 



ITS USE EXPLAINED. 117 

humus upon vegetation is explained by the foregoing 
facts, in the most clear and satisfactory manner. 

Humus does not nourish plants, by being taken up 
and assimilated in its unaltered state, but by presenting 
a slow and lasting source of carbonic acid which is ab- 
sorbed by the roots, and is the principal nutriment of 
young plants at a time when, being destitute of leaves, 
they are unable to extract food from the atmosphere. 

In former periods of the earth's history, its surface 
was covered with plants, the remains of which are still 
found in the coal formations. These plants, — the gigan- 
tic monocotyledons, ferns, palms, and reeds, belong to a 
class, to which nature has given the power, by means 
of an immense extension of their leaves, to dispense 
with nourishment from the soil. They resemble, in 
this respect, the plants which we raise from bulbs 
and tubers, and which live while young upon the sub- 
stances contained in their seed, and require no food 
from the soil, when their exterior organs of nutrition are 
formed. This class of plants is, even at present, ranked 
amongst those which do not exhaust the soil. 

The plants of every former period are distinguished 
from those of the present by the inconsiderable devel- 
opment of their roots. Fruit, leaves, seeds, nearly 
every part of the plants of a former world, except the 
roots, are found in the brown coal formation. The 
vascular bundles, and the perishable cellular tissue, of 
which their roots consisted, have been the first to suffer 
decomposition. But when we examine oaks and other 
trees, which in consequence of revolutions of the same 
kind occurring in later ages have undergone the same 
changes, we never find their roots absent. 

The verdant plants of warm climates are very often 



118 ORIGIN AND ACTION OP HUMUS. 

such as obtain from the soil only a point of attach- 
ment and are not dependent on it for their growth. 
How extremely small are the roots of the Cactus, Se- 
dum, and Seinpervivum, in proportion to their mass, 
and to the surface of their leaves ! Again, in the most 
dry and barren sand, where it is impossible for nourish- 
ment to be obtained through the roots, we see the 
milky-juiced plants attain complete perfection. The 
moisture necessary for the nutrition of these plants is 
derived from the atmosphere, and when assimilated is 
secured from evaporation by the nature of the juice it- 
self. Caoutchouc and wax, which are formed in these 
plants, surround the water, as in oily emulsions, with an 
impenetrable envelope by which the fluid is retained, in 
the same manner as milk is prevented from evaporating, 
by the skin which forms upon it. These plants, there- 
fore, become turgid with their juices. 

Particular examples might be cited of plants, which 
have been brought to maturity, upon a small scale, without 
the assistance of mould ; but fresh proofs of the accura- 
cy of our theory respecting the origin of carbon would 
be superfluous and useless, and could not render more 
striking, or more convincing, the arguments already ad- 
duced. It must not, however, be left unmentioned, that 
common wood charcoal, by virtue merely of its ordinary 
well-known properties, can completely replace vegetable 
mould or humus. The experiments of Lukas, which 
are appended to this work, spare me all further remarks 
upon its efficacy. 

Plants thrive in powdered charcoal, and may be 
brought to blossom and bear fruit if exposed to the in- 
fluence of the rain and the atmosphere ; the charcoal 
may be previously heated to redness. Charcoal is the 



ACTION OF CARBONIC ACID. 119 

nost "indifferent" and most unchangeable substance 
cnovvn ; it may be kept for centuries without change, 
md is therefore not subject to decomposition. The only 
iubstances which it can yield to plants are some salts, 
ivhich it contains, amongst which is silicate of potash, 
[t is known, however, to possess the power of condens- 
ng gases within its pores, and particularly carbonic acid. 
And it is by virtue of this power that the roots of plants 
ire supplied in charcoal exactly as in humus, with an at- 
mosphere of carbonic acid and air, which is renewed as 
:juickly as it is abstracted. 

In charcoal powder, which had been used for this pur- 
pose by Lukas for several years, Buchner found a brown 
substance soluble in alkalies. This substance was evi- 
dently due to the secretions from the roots of the plants 
which grew in it. 

A plant placed in a closed vessel in which the air, and 
therefore the carbonic acid, cannot be renewed, dies 
exactly as it would do in the vacuum of an air-pump, or 
in an atmpsphere of nitrogen or carbonic acid, even 
though its roots be fixed in the richest mould.* 

Plants do not, however, attain maturity, under ordinary 

* A few ^lears since I had an opportunity of observing a striking 
instance of the effect of carbonic acid upon vegetation in the vol- 
canic island of St. Michael (Azores). The gas issued from a fissure 
in the base of a hill of trachyte and tufta from which a level field of 
some acres extended. This field, at the time of my visit, was in part 
covered with Indian corn. The corn at the distance of ten or fifteen 
yards from the fissure, was nearly full grown, and of the usual height, 
but the height regularly diminished until within five or six feet of the 
hill, where it attained but a few inches. This effect was owing to the 
great specific gravity of the carbonic acid, and its spreading upon the 
ground, but as the distance increased, and it became more and more 
mingled with atmospheric air, it had produced less and less effect. — W. 



120 ASSIMILATION OF HYDROGEN. 

circumstances, in charcoal powder, when they are mois- 
tened with pure distilled water instead of rain or river 
water. Rain water must, therefore, contain within it 
one of the essentials of vegetable life ; and it will be 
shown, that this is the presence of a compound contain- 
ing nitrogen, the exclusion of which entirely deprives 
humus and charcoal of their influence upon vegetation. 



CHAPTER IV. 

ON THE ASSIMILATION OF HYDROGEN. 

The atmosphere contains the principal food of plants 
in the form of carbonic acid, in the state, therefore, of 
an oxide. The solid part of plants (woody fibre) con- 
tains carbon and the constituents of water, or the ele- 
ments of carbonic acid together with a certain quantity 
of hydrogen. We can conceive the wood to arise from 
a combination of the carbon of the carbonic acid with 
the elements of water, under the influence of solar light. 
In this case, 72.35 parts of oxygen, by weight, must be 
separated as a gas for every 27.65 parts of carbon, which 
are assimilated by a plant. Or, what is much more 
probable, plants, under the same circumstances, may de- 
compose water, the hydrogen of which is assimilated 
along with carbonic acid, whilst its oxygen is separated. 
If the latter change takes place, 8.04 parts of hydrogen 
must unite with 100 parts of carbonic acid, in order to 
form woody fibre, and the 72.35 parts by weight of oxy- 
gen, which was in combination with the hydrogen of the 
water, and which exactly corresponds in quantity with 



ASSIMILATION OF HYDROGEN. 121 

the oxygen contained in the carbonic acid, must be sep- 
arated in a gaseous form. 

Each acre of land, which produces 10 centners or 
cvvts. of carbon, gives annually to the atmosphere 2600 
Hessian lbs. of free oxygen gas. The specific weight 
of oxygen is expressed by the number 1.1026, hence 1 
cubic metre of oxygen weighs 2.864 Hessian lbs., and 
2600 lbs. of oxygen correspond to 90S cubic metres or 
58,112 Hessian cubic feet. 

An acre of meadow, wood, or cultivated land in gen- 
eral, replaces, therefore, in the atmosphere as much oxy- 
gen as is exhausted by 8 centners of carbon, either in its 
ordinary combustion in the air or in the respiratory pro- 
cess of animals. 

It has been mentioned at a former page that pure- 
woody fibre contains carbon and llie component parts of 
water, but that ordinary wood contains more hydrogen 
than corresponds to this proportion. This excess is 
owing to the presence of the green principle of the leaf,, 
wax, resin, and other bodies rich in hydrogen. Water 
must be decomposed, in order to furnish the excess of 
this element, and consequently one equivalent * of oxygen 
must be given back to the atmosphere for every equiva- 
lent of hydrogen appropriated by a plant to the produc- 
tion of those substances. The quantity of oxygen thus 
set at liberty cannot be insignificant, for the atmosphere 
must receive 989 cubic feet of oxygen for every pound 
of hydrogen assimilated. 

* Equivalent, the combining proportion of a substance. Elemen- 
tary bodies combine with each other in certain proportional quantities 
only, which are expressed by numbers, and those numbers are called 
equivalents, combining-proportions, or projjortions of the elements. 
The equivalent of a compound body is tlie sum of the equivalents of,' 
its constituents. See Introduction p. 34. 
\l 



122 ASSIMILATION OF HyDROGEN 

It has already been stated, that a plant, in the forma- 
tion of woody fibre, must always yield to the atmo- 
sphere the same proportional quantity of oxygen ; that 
the volume of this gas set free would be the same 
whether it were due to the decomposition of carbonic 
acid or of water. It was considered most probable that 
the latter was the case. 

From their generating caoutchouc, wax, fats, and 
volatile oils containing hydrogen in large quantity, and 
no oxygen, we may be certain that plants possess the 
property of decomposing water, because from no other 
body could they obtain the hydrogen of those matters. 
It has also been proved by the observations o( Humboldt 
on the fungi, that water may be decomposed without 
the assimilation of hydrogen. Water is a remarkable 
combination of two elements,* which have the power to 
separate themselves from one another, in innumerable 
processes, in a manner imperceptible to our senses ; 
while carbonic acid, on the contrary, is only decompo- 
sable by violent chemical action. 

Most vegetable structures contaiji hydrogen in the 
form of water, which can be separated as such, and 
replaced by other bodies ; but the hydrogen which is 
essential 1o their constitution cannot possibly exist in 
the state of water. 

All the hydrogen necessary for the formation of an 
organic compound is supplied to a plant by the decom- 
position of water. The process of assimilation, in its 
most simple form, consists in the extraction of hydro- 
gen from water, and carbon from carbonic acid, in con- 

* Water is composed of two volumes of hydrogen and one volume 
of oxygen ; by weight, of 1 hydrogen and 8 oxygen. 



ATTENDED WITH EVOLUTION OF OXSGEN. 123 

sequence of which, either all the oxygen of the water 
and carbonic acid is separated, as in the formation of 
caoutchouc, the volatile oils which contain no oxygen, 
and other similar substances, or only a part of it is ex- 
haled. 

The known composition of the organic compounds 
most generally present in vegetables, enables us to state 
in definite proportions the quantity of oxygen separated 
during their formation. 

3G eq. carbonic acid and 22 eq. hydrogen ) ^ ^^^ . ^.^^^ 
derived from 22 eq. water ) " 

with the separation of 72 eq. oxygen. 

3G eq. carbonic acid and 36 eq. hydrogen ) 'iuaar 

derived from 36 eq. water 5 = > 

with the separation of 72 eq. oxygen. 

3G eq. carbonic acid and 30 eq. hydrogen 7 ^. , 

derived from 30 eq. water 5 ' 

with the separation of 72 eq. oxygen. 

36 eq. carbonic acid and 16 eq. hydrogen) ™ . „ ., 

derived from 16 eq. water ) ' 

with the separation of 64 eq. oxygen. 

36 eq. carbonic acid and 18 eq. hydrogen ) t> , • /j • j 

derived from 18 eq. water 5 — ^'^"'^'"^'^ •*'"'^. 

with the separation of 45 eq. oxygen. 

36 eq. carbonic acid and 18 eq hydrogen ) ., ,. /,-.,, 

derived from 18 eq. water 5 ~ •^^"'*'^ •*"^' 

with the separation of 54 eq. oxygen. 

36 eq. carbonic acid and 24 eq. hydroffen ) /r? /• ^ 

derived from 24 eq. water ^ = Oil of Turpentine, 

with the separation of 84 eq. oxygen. 

It will readily be perceived that the formation of the 
acids is accompanied with the smallest separation of 
oxygen ; that the amount of oxygen set free increases 
with the production of the so named neutral substances, 
and reaches its maximum in the formation of the oils. 



* An acid discovered in the juice of the apple, and since in the ber- 
ries of the mountain ash. 



124 ASSIMILATION OF HYDROGEN 

Fruits remain acid in cold summers ; while the most 
numerous trees under the tropics are those which pro- 
duce oils, caoutchouc, and other substances, containing 
very little oxygen. The action of sunshine and influ- 
ence of heat, upon the ripening of fruit, is thus in a 
certain measure represented by the numbers above 
cited. 

The green resinous principle of the leaf diminishes 
in quantity, while oxygen is absorbed, when fruits are 
ripened in the dark ; red and coloring matters are form- 
ed ; tartaric, citric, and tannic acids disappear, and are 
replaced by sugar, amylin, or gum. 6 eq. Tartaric 
Acid, by absorbing 6 eq. oxygen from the air, form 
Grape Sugar, with the separation of 12 eq. carbonic 
acid. 1 eq.' Tannic ^cid, by absorbing 8 eq. oxygen 
from the air, and 4 eq. water form 1 eq. of Amylin, or 
starch, with separation of 6 eq. cai'bonic acid. 

We can explain, in a similar manner, the formation 
of all the component substances of plants, which con- 
tain no nitrogen, whether they are produced from car- 
bonic acid and water, with separation of oxygen, or by 
the conversion of one substance into the other, by the 
assimilation of oxygen and separation of carbonic acid. 

We do not know in what form the production of 
these constituents takes place ; in this respect, the rep- 
resentation of their formation which we have given must 
not be received in an absolute sense, it being intended 
only to render the nature of the process more capable 
of apprehension ; but it must not be forgotten, that if 
the conversion of tartaric acid into sugar, in grapes, be 
considered as a fact, it must take place under all cir- 
cumstances in the same proportions. 

The vital process in plants is, with reference to the 



BY THE DECOMPOSITION OF WATER. 125 

point we have been considering, the very reverse of the 
chemical processes engaged in the formation of salts. 
Carbonic acid, zinc, and water, when brought into con- 
tact, act upon one another, and hydrogen is sepafated 
while a white pulverulent compound is formed, which 
contains carbonic acid, zinc, and the oxygen of the 
water. A living plant represents the zinc in this pro- 
cess : but the process of assimilation gives rise to com- 
pounds, which contain the elements of carbonic acid 
and'the hydrogen of water, whilst oxygen is separated. 

Decay has been described above as the great opera- 
tion of nature, by which that oxygen, which was assimi- 
lated by plants during life, is again returned to the at- 
mosphere. During the progress of growth, plants 
appropriate carbon in the form of carbonic acid, and, 
hydrogen from the decomposition of water, the oxygen 
of which is set free, together with a part or all of that 
contained in the carbonic acid. In the process of 
putrefaction, a quantity of water, exactly corresponding 
to that of the hydrogen, is again formed by extraction 
of oxygen from the air ; while all the oxygen of the 
organic matter is returned to the atmosphere in the 
form of carbonic acid. Vegetable matters can emit 
carbonic acid, during their decay, only in proportion to 
the quantity of oxygen which they contain ; acids, 
therefore, yield more carbonic acid than neutral com- 
pounds ; while fatty acids, resin, and wax, do not 
putrefy, they remain in the soil without any apparent 
change. 

The numerous springs which emit carbonic acid in 
the neighbourhood of extinct volcanoes, must be re- 
garded as another considerable source of oxygen. Bis- 
chof calculated that the springs of carbonic acid in the 
11* 



126 SOURCE AND ASSIMILATION 

Eifel (a volcanic district near Coblenz) send into the 
air every day more than 90,000 lbs. of carbonic acid, 
corresj3onding to 64,800 lbs. of pure oxygen. 



CHAPTER V. 

ON THE ORIGIN AND ASSIMILATION OF NITROGEN. 

We cannot suppose that a plant would attain matu- 
rity, even in the richest vegetable mould, without the 
presence of matter containing nitrogen ; since we know 
that nitrogen exists in every part of the vegetable struc- 
ture. The first and most important question to be 
solved, therefore, is : How and in what form does 
nature furnish nitrogen to vegetable albumen, and glu- 
ten, to fruits and seeds ? 

This question is susceptible of a very simple solution. 

Plants, as we know, grow perfectly well in pure 
■charcoal, if supplied at the same time with rain-water. 
Rain-water can contain nitrogen only in two forms, 
•either as dissolved atmospheric air, or as ammonia. 
Now, the nitrogen of the air cannot be made to enter 
into combination with any element except oxygen, even 
by employment of the most powerful chemical means. 
We have not the slightest reason for believing that the 
nitrogen of the atmosphere takes part in the processes 
of assimilation of plants and animals ; on the contrary, 
we know that many plants emit the nitrogen, which is 
absorbed by their roots, either in the gaseous form, or 
in solution in water. But there are, on the other hand. 



OF THE NITROGEN OF PLANTS. 127 

numerous facts, showing, that the formation in plants of 
substances containing nitrogen, such as gluten, takes 
place in proportion to the quantity of this element which 
is conveyed to their roots in the state of ammonia,* 
derived from the putrefaction of animal matter. 

Ammonia, too, is capable of undergoing such a multi- 
tude of transformations, when in contact with other 
bodies, that in this respect it is not inferior to water, 
which possesses the same property in an eminent degree. 
It possesses properties which we do not find in any 
other compound of nitrogen ; when pure, it is extreme- 
ly soluble in water ; it forms soluble compounds with 
all the acids ; and when in contact with certain other 
substances, it completely resigns its character as an 
alkali, and is capable of assuming the most various and 
opposite forms. Formate f of ammonia changes, under 
the influence of a high temperature, into hydrocyanic 
acid and water, without the separation of any of its ele- 
ments. Ammonia forms urea,| with cyanic acid,§ and 

* Ammonia is a compound gas consisting of one volume of nitro- 
gen and three volumes of hydrogen. It is produced during the 
decomposition of many animal substances. It is given off when sal- 
ammoniac and lime are rubbed together. It was formerly called 
volatile alkali. 

t Formic acid is also obtained from sugar and many other vegetable 
substances; a pound of sugar yields a quantity capable of saturating 
five or six ounces of carbonate of lime. A process for obtaining it 
has been given by Emmet in the American Journal, XXXII. p. 140. 
See details in Webster's Manual of Clicmislrij, 3d edition, p. 374. 

Its composition is carbon 2, water 3. With ammonia and other 
bases it yields the salts cMed formates. 

X Urea was discovered in urine, being a constituent of uric acid. 
It contains the elements of cyanate of ammonia (NH4O -f- C4NO). 

§ This acid consists of 1 cyanogen and 1 oxygen. See Webster's 
Chemistry, p. 31)8. 



128 SOURCE AND ASSIMILATION 

a series of crystalline compounds, with the volatile oils 
of mustard and bitter almonds. It changes into splen- 
did blue or red coloring matters, when in contact with 
the bitter constituent of the bark of the apple-tree 
{phloridzin) , with the sweet principle of the Variolaria 
dealbata (orcin)^ or with the tasteless matter of the 
Rocella tinctoria (erythrin). All blue coloring mat- 
ters which are reddened by acids, and all red coloring 
substances which are rendered blue by alkalies, contain 
nitrogen, but not in the form of a base. 

These facts are not sufficient to establish the opinion 
that it is ammonia, which affords all vegetables without 
exception the nitrogen which enters into the composi- 
tion of their constituent substances. Considerations of 
another kind, however, give to this opinion a degree of 
certainty, which completely excludes all other views of 
the matter. 

Let us picture to ourselves the condition of a well 
cultured farm, so large as to be independent of assis- 
tance from other quarters. On this extent of land there 
is a certain quantity of nitrogen contained both in the 
corn and fruit which it produces, and in the men and 
animals which feed upon them, and also in their excre- 
ments. We shall suppose this quantity to be known. 
The land is cultivated without the importation of any 
foreign substance containing nitrogen. Now, the pro- 
ducts of this farm must be exchanged every year for 
money, and other necessaries of life, for bodies, there- 
fore, which contain no nitrogen. A certain proportion 
of nitrogen is exported with corn and cattle ; and this 
exportation takes place every year, without the smallest 
compensation ; yet after a given number of years, the 
quantity of nitrogen will be found to have increased. 



OF THE NITROGEN OF PLANTS. 129 

Whence, we may ask, comes this increase of nitrogen ? 
The nitrogen in the excrements cannot reproduce itself, 
and the earth cannot yield it. Plants, and consequently 
animals, must, therefore, derive their nitrogen from the 
atmosphere. 

The last products of the decay and putrefaction of 
animal bodies present themselves in two different forms. 
They are in the form of a combination of hydrogen and 
nitiogen, — ammonia^ in the temperate and cold cli- 
mates, and in that of a compound, containing oxygen, 
nitric acid, in the tropics and hot climates. The for- 
mation of the latter is preceded by the production of the 
first. Ammonia is the last product of the putrefaction 
of animal bodies ; nitric acid is the product of the trans- 
formation of ammonia. A generation of a thousand 
million men is renewed every thirty years : thousands of 
millions of animals cease to live, and are reproduced in 
a much shorter period. Where is the nitrogen which 
they contained during life .'' There is no question 
which can be answered with more positive certainty. 
All animal bodies, during their decay, yield the nitrogen, 
which they contain to the atmosphere, in the form of 
ammonia. Even in the bodies buried sixty feet under 
ground in the churchyard of the £glise des Innocens, at 
Paris, all the nitrogen contained in the adipocire was in 
the state of ammonia.* Ammonia is the simplest of all 

* In 1786-7, when this churchyard was cleared out, it was discov- 
ered that many of the bodies had been converted into a soapy white 
substance. Fourcroy attempted to prove that the fatty body was an 
ammoniacal soap, containing phosphate of hme, that the fat was simi- 
lar to spermaceti and to wax, hence he called it adipocire. Its melt- 
ing point was 126.5° F. 

For notice of the analysis and opinions of other chemists see Ure's 
Dictionary of^rts and Manufactures, p. 14. 



130 SOURCE AND ASSIMILATION 

the compounds of nitrogen ; and hydrogen is the ele- 
ment for which nitrogen possesses the most powerful 
affinity. 

The nitrogen of putrefied animals is contained in the 
atmosphere as ammonia, in the form of a gas which is 
capable of entering into combination with carbonic acid, 
and of forming a volatile salt. Ammonia in its gaseous 
form as well as all its volatile compounds are of extreme 
solubility in water. * Ammonia, therefore, cannot re- 
main long in the atmosphere, as every shower of rain 
must condense it, and convey it to the surface of the 
earth. Hence, also, rain-water must, at all times, con- 
tain ammonia, though not always in equal quantity. It 
must be greater in summer than in spring or in winter, 
because the intervals of time between the showers are 
in summer greater ; and when several wet days occur, 
the rain of the first must contain more of it than that of 
the second. The rain of a thunder-storm, after a long 
protracted drought, ought for this reason to contain the 
greatest quantity, which is conveyed to the earth at one 
time. 

But all the analyses of atmospheric air, hitherto made, 
have failed to demonstrate the presence of ammonia, 
although according to our view it can never be absent. 
Is it possible that it could have escaped our most 
delicate and most exact apparatus .'' The quantity of 
nitrogen contained in a cubic foot of air is certainly 
extremely small, but notwithstanding this, the sum of 
the quantities of nitrogen from thousands and millions of 
dead animals is more than sufficient to supply all those 
living at one time with this element. 

* According to Dr. Thomson, water absorbs 780 times its bulk of 
ammonia. 



OF THE NITROGEN OF PLANTS. 131 

From the tension of aqueous vapor at 15° C. (59° 
F.) = 6.98 lines (Paris measure) and from its known 
specific gravity at 0° C. (32° F.), it follows that when 
the temperature of the air is 59^ F. and the height of 
the barometer 28'', 1 cubic metre or 64 Hessian cubic 
feet of aqueous vapor are contained in 487 cubic me- 
tres, or 31,168 cubic feet of air ; 64 feet of aqueous 
vapor weigh about 1^ lb. Consequently if we suppose 
that the air saturated with moisture at 59° F. allows all 
the water which it contains in the gaseous form to fall as 
rain ; then 1 Hessian pound of rain-water must be ob- 
tained from every 20,800 cubic feet of air. The whole 
quantity of ammonia contained in the same number of 
cubic feet will also be returned to the earth in this one 
pound of rain-water. But if the 20,800 cubic feet of 
air contain a single grain of ammonia, then ten cubic 
inches, the quantity usually employed in an analysis, 
must contain only 0.000000048 of a grain. This ex- 
tremely small proportion is absolutely inappreciable by 
the most delicate and best eudiometer ; * it might be 
classed among the errors of observation, even were its 
quantity ten thousand times greater. But the detection 
of ammonia must be much more easy, when a pound 
of rain-water is examined, for this contains ail the gas 
that was diffused through 20,800 cubic feet of air. 

If a pound of rain-water contain only |th of a grain 
of ammonia, then a field of 40,000 square feet must 
receive annually upwards of 80 lbs. of ammonia, or 65 
lbs. of nitrogen ; for, by the observations of Sch'Mcr, 

* A eudiometer is an instrument used in the analysis of the atmo- 
sphere. It means a measure of purity. It is also used in the analysis 
of mixtures of gases. Several varieties a'e described in Webster's 
Manual, p. 137. 



132 SOURCE AND ASSIMILATION 

which were formerly alluded to, about 700,000 lbs. of 
rain fall over this surface in four months, and conse- 
quently the annual fall must be 2,500,000 lbs. This is 
much more nitrogen than is contained in the form of 
vegetable albumen and gluten, in 2650 lbs. of wood, 
2800 lbs. of hay, or 200 cwt. of beet-root, which are 
the yearly produce of such a field, but it is less than the 
straw, roots, and grain of corn which might grow on the 
same surface, would contain. 

Experiments, made in this laboratory (Giessen) with 
the greatest care and exactness, have placed the presence 
of ammonia in rain-water beyond all doubt. It has 
hitherto escaped observation, because no person thought 
of searching for it.* All the rain-water employed in 
this inquiry was collected 600 paces southwest of Gies- 
sen, whilst the wind was blowing in the direction of the 
town. When several hundred pounds of it were distilled 
in a copper still, and the first two or three pounds evapo- 
rated with the addition of a little muriatic acid, a very 
distinct crystallization of sal-ammoniac was obtained : the 
crystals had always a brown or yellow color. 

Ammonia may likewise be always detected in snow- 
water. Crystals of sal-ammoniac were obtained by 
evaporating in a vessel with muriatic acid several pounds 
of snow, which were gathered from the surface of the 
ground in March, when the snow had a depth of 10 
inches. Ammonia was set free from these crystals by 
the addition of hydrate of lime. The inferior layers 
of snow, which rested upon the ground, contained a 
quantity decidedly greater than those which formed the 
surface. 

* It has been discovered by Mr. Hayes in the rain-water in Ver- 
mont. 



OF THE NITROGEN OF PLANTS. 133 

It is worthy of observation, that the ammonia con- 
tained in rain and snow water, possessed an offensive 
smell of perspiration and animal excrements, — a fact 
which leaves no doubt respecting its origin. 

H'dnefeld has proved, that all the springs in Greifs- 
walcle^ Wick, Eldena, and Kostenhagen, contain CBr- 
bonate and nitrate of ammonia. Ammoniacal salts have 
been discovered in many mineral springs in Kissingen 
and other places. The ammonia of these salts can only 
arise from the atmosphere.* 

Any one may satisfy himself of the presence of am- 
monia in rain, by simply adding a little sulphuric or 
muriatic acid to a quantity of rain-water, and evaporating 
this nearly to dryness in a clean porcelain basin. The 
ammonia remains in the residue, in combination with the 
acid employed ; and may be detected either by the 
addition of a little chloride of platinum, or more simply- 
by a little powdered lime, which separates the ammonia,, 
and thus renders its peculiar pungent smell sensible.. 
The sensation which is perceived upon moistening the- 
hand with rain-water, so different from that produced by 
pure distilled water, and to which the term softness is 
vulgarly applied, is also due to the carbonate of ammonia 
contained in the former. f 

The ammonia, which is removed from the atmosphei-e- 
by rain and other causes, is as constantly replaced by 

* Professor Daubeny, of Oxford, in his Report on Mineral and' 
Thermal Waters, to the British Association, in 1836, notices the 
occurrence of ammonia in various springs, and refers its presence- 
to the decomposition of animal or vegetable substances where the- 
springs are not connected with volcanic action. 

+ A small quantity of ammonia wafer added to what is commonly 
called hard water, will give it the softness of rain or snow water. 

12 



134 SOURCE AND ASSIMILATION 

the putrefaction of animal and vegetable matters. A cer- 
tain poriion of that which falls with the rain, evaporates 
again with the water, but another portion is, we suppose, 
taken up by the roots of plants, and, entering into new 
combinations in the different organs of assimilation, pro- 
duces albumen, gluten, quinine, morphia, cyanogen, and 
a number of otiier compounds containing nitrogen. The 
chemical characters of ammonia render it capable of 
entering into such combinations, and of undergoing nu- 
merous transformations. We have now only to con- 
sider whether it really is taken up in the form of ammonia 
by the roots of plants, and in that form applied by their 
organs to the production of the azotized matters con- 
tained in them. This question is susceptible of easy 
solution by well-known facts. 

In the year 1834, I was engaged with Dr. JVilbrand, 
Professor of Botany in the University of G lessen, in an 
investigation respecting the quantity of sugar contained 
in different varieties of maple-trees, which grew upon 
soils which were not manured. We obtained crystallized 
sugars from all, by simply evaporating their juices, with- 
out the addition of any foreign substance ; and we un- 
expectedly made the observation, that a great quantity 
of ammonia was emitted from this juice, when mixed 
with lime, and also from the sugar itself during its refine- 
ment. The vessels, which hung upon the trees in order 
to collect the juice, were watched with greater attention, 
on account of the suspicion that some evil-disposed 
persons had introduced urine into them, but still a large 
quantity of ammonia was again found in the form of 
neutral salts. The juice had no color, and had no re- 
action on that of vegetables. Similar observations were 
made upon the juice of the birch-tree ; the specimens 



OF THE NITROGEN OF PLANTS. 135 

subjected to experiment were taken from a wood several 
miles distant from any house, and yet the clarified juice, 
evaporated with lime, emitted a strong odor of ammonia. 

In the manufactories of beet-root sugar, many thou- 
sand cubic feel of juice are daily purified with lime, in 
order to free it from vegetable albumen and gluten, and 
it is afterwards evaporated for crystallization. Every 
person, who has entered such a manufactory, must have 
been astonished at the great quantity of ammonia which 
is volatilized along with the steam. This ammonia must 
be contained in the form of an ammoniacal salt, because 
the neutral juice possesses the same characters as the 
solution of such a salt in water ; it acquires, namely, an 
acid reaction during evaporation, in consequence of the 
neutral salt being converted by loss of ammonia into an 
acid salt. The free acid which is thus formed is a 
source of loss to the manufacturers of sugar from beet- 
root, by changing a part of the sugar into uncrystallizable 
grape sugar and syrup. 

The products of the distillation of flowers, herbs, and 
roots, with water, and all extracts of plants made for 
medicinal purposes, contain ammonia. The unripe, 
transparent, and gelatinous pulp of the almond and peach 
emit much ammonia when treated with alkalies. {Robi- 
quet.) The juice of the fresh tobacco leaf contains 
ammoniacal salts. The water, which exudes from a cut 
vine, when evaporated with a few drops of muriatic acid, 
also yields a gummy deliquescent mass, which evolves 
much ammonia on the addition of lime. Ammonia ex- 
ists in every part of plants, in the roots (as in beet-root), 
in the stem (of the maple-tree), and in all blossoms and 
fruit in an unripe condition. 

The juices of the maple and birch contain both sugar 



136 SOURCE AND ASSIMILATION 

and ammonia, and, therefore, afford all the conditions 
necessary for the formation of the azotized components 
of the branches, blossoms, and leaves, as well as of those 
which contain no azote or nitrogen. In proportion as 
the development of those parts advances, the ammonia 
diminishes in quantity, and when they are fully formed, 
the tree yields no more juice. 

The employment of animal manure in the cultivation 
of grain, and the vegetables which serve for fodder to 
cattle, is the most convincing proof that the nitrogen of 
vegetables is derived from ammonia. The quantity of 
gluten in wheat, rye, and barley, is very different ; these 
kinds of grain also, even when ripe, contain this com- 
pound of nitrogen in very different proportions. Proust 
found French wheat to contain 12.5 per cent, of gluten ; 
Vogcl found that the Bavarian contained 24 per cent. ; 
Davy obtained 19 per cent, from winter, and 24 from 
summer wheat ; from Sicilian 21, and from Barbary 
wheat 19 per cent. The meal of Alsace wheat contains, 
according to Boussingault., 17.3 per cent, of gluten ; 
that of wheat grown in the " Jardin des Plantes " 26.7, 
and that of winter wheat 3.33 per cent. Such great 
differences must be owing to some cause, and this we 
find in the different methods of cultivation. An increase 
of animal manure gives rise not only to an increase in 
the number of seeds, but also to a most remarkable dif- 
ference in the proportion of the gluten which they con- 
tain. 

Animal manure, as we shall afterwards show, acts only 
by the formation of ammonia. One hundred parts of 
wheat grown on a soil manured with cow-dung (a manure 
containing the smallest quantity of nitrogen), afforded 
only 11.95 parts of gluten, and 64.34 parts of amylin, 



OF THE NITROGEN OF PLANTS. 137 

or Starch ; whilst the same quantity, grown on a soil 
manured with human urine, yielded the maximum of glu- 
ten, namely 35.1 per cent. Putrified urine contains 
nitrogen in the forms of carbonate, phosphate, and lac- 
tate of ammonia, and in no other form than that of am- 
moniacal salts. 

" Putrid urine is employed in Flanders as a manure 
with the best results. During the putrefaction of urine, 
ammoniacal salts are formed in large quantity, it may be 
said exclusively ; for under the influence of heat and 
moisture urea, the most prominent ingredient of the urine, 
is converted into carbonate of ammonia. The barren 
soil on the coast of Peru is rendered fertile by means of 
a manure called guano^ which is collected from several 
islands on the South Sea.* Tt is sufficient to add a 
small quantity of guano to a soil, which consists only of 
sand and clay, in order to procure the richest crop of 
maize. The soil itself dues not contain the smallest 
particle of organic matter, and the manure employed is 
formed only of urate, phosphate, oxalate, and carbonate 
of ammonia, together with a few earthy salts." f 

iVmmonia, therefore, must have yielded the nitrogen 
to these plants. Gluten is obtained not only from corn, 
but also from grapes and other plants ; but that extracted 
from the grapes is called vegetable albumen, although it 
is identical in composition and properties with the ordi- 
nary gluten. 

* The guano, which forms a sl/atum of several feet in thickness 
upon the surface of these islands, consists of the putrid excrements 
of innumerable sea-fowl that remain on them during the breeding 
season. 

According to Fourcroy and Vauquelin it contains a fourth part of 
its weight of uric acid, with ammonia and potash. 

t Boussingault, Jinn, de Chim. et de Pkys. t. Ixv. p. 319. 

12* 



138 SOURCE AND ASSIMILATION 

It is ammonia which yields nitrogen to the vegetable 
albumen, the principal constituent of plants ; and it must 
be ammonia which forms the red and blue coloring mat- 
ters of flowers. Nitrogen is not presented to wild plants 
in any other form capable of assimilation. Ammonia, 
by its transformation, furnishes nitric acid to the tobacco 
plant, sunflower, Chenopoclium, and Borago officinalis^ 
when they grow in a soil completely free from nitre. 
Nitrates are necessary constituents of these plants, which 
thrive only when ammonia is present in large quantity, 
and when they are also subject to the influence of the 
direct rays of the sun, an influeiice necessary to effect 
the disengagement within their stem and leaves of the 
oxygen, which shall unite with the ammonia to form nitric 
acid. 

The urine of men and of carnivorous animals contains 
a large quantity of nitrogen, partly in the form of phos- 
phates, partly as urea. Urea is converted during putre- 
faction into carbonate of ammonia, thai is to say, it takes 
the form of the very salt which occurs in rain-water. 
Human urine is the most powerful manure for all vege- 
tables containing nitrogen ; that of horses and horned 
cattle contains less of this element, but infinitely more 
than the solid excrements of these animals. In addition 
to urea, the urine of herbivorous animals contains hippuric 
acid,* which is decomposed during putrefaction into 
benzoic acid f and ammonia. The latter enters into the 

* Rouelle announced the discovery of an acid in the urine of the 
horse, which he called benzoic, but in 1834 Liebig showed that this 
was not benzoic acid, but one easily convertible into it, and distin- 
guished it by the name hippuric, from "vxos, a horse, and alggp, mine. 

t Benzoic acid exists in gum benzoin, »fcc. ; it is formed, according 
to Liebig, by the oxidation of a supposed base called benziile. Its 
composition is carbon 14, hydrogen 5, oxygen 2. 



OF THE NITROGEN OF PLANTS. 139 

composition of the gluten, but the benzoic acid often 
remains unchanged : for example, in the Jlnthoxanlhum 
odoratum (sweet scented spring grass). 

The solid excrements of animals contain comparative- 
ly very little nitrogen, but this could not be otherwise. 
The food taken by animals supports them only in so far 
as it offers elements for assimilation to the various organs, 
which they may require for their increase or renewal. 
Corn, grass, and all plants, without exception, contain 
azotized substances.* The quantity of food, which 
animals take for their nourishment, diminishes or increases 
in the same proportion, as it contains more or less of the 
substances containing nitrogen. A horse may be kept 
alive by feeding it with potatoes, which contain a very 
small quantity of nitrogen ; but life thus supported is a 
gradual starvation ; the animal increases neither in size 
nor strength, and sinks under every exertion. The 
quantity of rice which an Indian eats astonishes the Eu- 
ropean ; but the fact, that rice contains less nitrogen than 
any other kind of grain, at once explains the circum- 
stance. f 

* The late Professor Gorliam obtained from Indian corn a substance 
to which he gave the name Zeine, according to whose analysis it con- 
tains no nitrogen ; but ammonia has since been obtained from it. 

t According to the analysis of Braconnot {^nn. dc Chim. et de 
Phys. t. iv. p. 370), this grain is thus constituted. 

Carolina rice. Picdmovt rice. 



Water, . . . 5.00 


7.00 


Starch, .... 85.07 


83 80 


Parenchyma, . . 4.80 


4 80 


Gluten, . . . 3.60 


3 60 


Uncrystallizable sugar, 0.29 


0.05 


Gummy matter approach- ? q yj 
ing to starch, \ ' 


0.10 


Oil, .... 0.13 


0.25 


Phosphate of lime, . 0.13 


40 



99.73 10000. With 



140 SOURCE AND ASSIMILATION 

Now, as it is evident that the nitrogen of the plants 
and seeds used by animals as food must be employed in 
the process of assimilation, it is natural to expect that 
the excrements of these animals will be deprived of it, 
in proportion to the perfect digestion of the food, and 
can only contain it when mixed with secretions from the 
liver and intestines. Under all circumstances, they must 
contain less nitrogen than the food. When, therefore, a 
field is manured with animal excrements, a smaller quan- 
tity of matter containing nitrogen is added to it than has 
been taken from it in the form of grass, herbs, or seeds. 
By means of manure, an addition only is made to the 
nourishment which the air supplies. 

In a scientific point of view, it should be the care of 
the agriculturist so to employ all the substances contain- 
ing a large proportion of nitrogen which his farm affords 
in the form of animal excrements, that they shall serve 
as nutriment to his own plants. This will not be the 
case unless those substances are properly distributed 
upon his land. A heap of manure lying unemployed 
upon his land would serve him no more than his neigh- 
bours. The nitrogen in it would escape as carbonate of 
ammonia into the atmosphere, and a mere carbonaceous 
residue of decayed plants would, after some years, be 
found in its place. 

All animal excrements emit carbonic acid and ammo- 
nia, as long as nitrogen exists in them. In every stage 
of their putrefaction an escape of ammonia from them 
may be induced by moistening them with a potash ley ; 

traces of muriate of polasli, phosphate of potash, acetic acid, sulphur, 
and lime, and potash united to a vegetable alkali. 

Vauquelin was unable to detect any saccharine matter in rice. — 
Thomson's Organic Chemistry, p. 883. 



OF THE NITROGEN OF PLANTS. 141 

the ammonia being apparent to the senses by a peculiar 
smell, and by the dense white vapor which arises when 
a solid body moistened with an acid is brought near it. 
This ammonia evolved from manure is imbibed by the 
soil either in solution in water, or in the gaseous form, 
and plants thus receive a larger supply of nitrogen than 
is afforded to them by the atmosphere. 

But it is much less the quantity of ammonia, yielded 
to a soil by animal excrements, than the form in which 
it is presented by them, that causes their great influence 
on its fertility. Wild plants obtain more nitrogen from 
the atmosphere in the form of ammonia than they re- 
quire for their growth, for the water which evaporates 
through their leaves and blossoms, emits, after some 
time, a putrid smell, a peculiarity possessed only by 
such bodies as contain nitrogen. Cultivated plants re- 
ceive the same quantity of nitrogen from the atmosphere 
as trees, shrubs, and other wild plants ; but this is not 
sufficient for the purposes of agriculture. Agriculture 
differs essentially from the cultivation of forests, inas- 
much as its principal object consists in the production 
of nitrogen under any form capable of assimilation ; 
whilst the object of forest culture is confined principally 
to the production of carbon. All the various means of 
culture are subservient to these two main purposes. A 
part only of the carbonate of ammonia, which is con- 
veyed by rain to the soil is received by plants, because 
a certain quantity of it is volatilized with the vapor of 
water ; only that portion of it can be assimilated which 
sinks deeply into the soil, or which is conveyed directly 
to the leaves by dew, or is absorbed from the air along 
with the carbonic acid. 

Liquid animal excrements, such as the urine with 



1 



142 SOURCE AND ASSIMILATEON 

which the solid excrements are impregnated, contain the 
greatest part of their ammonia in the slate of sahs, in a 
form, therefore, in which it has completely lost its vola- 
tility when presented in this condition ; not the smallest 
portion of the ammonia is lost to the plants, it is all dis- 
solved by water, and imbibed by their roots. The evi- 
dent influence of gypsum upon the growth of grasses, — 
the striking fertility and luxuriance of a meadow upon 
which it is strewed, — depends only upon its fixing in 
the soil the ammonia of the atmosphere, which would 
otherwise be volatilized, with the water which evapo- 
rates. The carbonate of ammonia contained in rain- 
water is decomposed by gypsum, in precisely the same 
manner as in the manufacture of sal-ammoniac. Solu- 
ble sulphate of ammonia and carbonate of lime are 
formed ; and this salt of ammonia possessing no volatil- 
ity is consequently retained in the soil. All the gyp- 
sum gradually disappears, but its action upon the car- 
bonate of ammonia continues as long as a trace of it 
exists. 

The benficial influence of gypsum and of many other 
salts has been compared to that of aromatics, which in- 
crease the activity of the human stomach and intestines, 
and give a tone to the whole system. But plants con- 
tain no nerves ; we know of no substance capable of 
exciting them to intoxication and madness, or of lulling 
them to sleep and repose. No substance can possibly 
cause their leaves to appropriate a greater quantity of 
carbon from the atmosphere, when the other constitu- 
ents which the seeds, roots, and leaves require for their 
growth are wanting.* The favorable action of small 

* In 1831, I suggested to a well known and most successful culti- 



OF THE NITROGEN OF PLANTS. 143 

quantities of aromatics upon man, when mixed with his 
food, is undeniable, but aromatics are given to plants 
loithout food to be digested, and still they flourish with 
greater luxuriance. 

It is quite evident, therefore, that the common view 
concerning the influence of certain salts upon the growth 
of plants evinces only ignorance of its cause. 

The action of gypsum or chloride of calcium (bleach- 
ing salts) really consists in their giving a fixed condi- 
tion to the nitrogen, — or ammonia which is brought 
into the soil, and which is indispensable for the nutrition 
of plants. 

In order to form a conception of the efl^ect of gyp- 
sum, it may be suflicient to remark that 100 Hess, lbs 
of burned gypsum fixes as much ammonia in the soil as 
6250 lbs. of horse's urine f would yield to it, even on the 
supposition that all the nitrogen of the urea and hippuric 
acid were absorbed by the plants without the smallest 

vator (Mr. Haggarston),the application of a weak solution of chlorine 
gas to the soil in which plants were growing. It appeared to act 
merely as a stimulant, the plants flourished for a time with great lux- 
uriance, and in some the foliage was remarkable. The leaves of a Pe- 
largonium (well known as the Washington Geranium) attained the 
diameter of a foot, but the flowers were by no means equal to those of 
similar plants cultivated in the usual manner ; the plants soon perish- 
ed. Probably a supply of nutriment proportioned to the increased de- 
mand was not supplied. 

The necessity for this supply is now well known, and Pelargoni- 
ums are now grown with great luxuriance and perfection, both of 
leaves and flowers, by the free use of "manure water," obtained by 
steeping horse dung in rain-water. The soil, too, best adapted to 
the plants is chiefly prepared fiom decayed vegetable matter, derived 
from decomposed leaves and plants mixed with that from the sods of 
fields. 

t Th3 urine of the horse contains, according to Four.croy and Vau- 
quelin, in 1000 parts, — 



144 SOURCE AND ASSIMILATION 

loss, in the form of carbonate of ammonia. If we admit 
with Boussingault,* that the nitrogen in grass amounts 
to t4o o^ '^^^ weight, then every pound of nitrogen which 
we add increases the produce of the meadow 100 lbs., 
and this increased produce of 100 lbs. is effected by the 
aid of a little more than four pounds of gypsum. 

Water is absolutely necessary to effect the decompo- 
sition of the gypsum, on account of its difficult solubil- 
ity, (I part of gypsum requires 400 parts of water for 
solution,) and also to assist in the absorption of the sul- 
phate of ammonia by the plants : hence it happens that 
the influence of gypsum is not observable on dry fields 
and meadows. 

The decomposition of gypsum by carbonate of am- 
monia does not take place instantaneously ; on the con- 
trary, it proceeds very gradually, and this explains why 
the action of the gypsum lasts for several years. 

The advantage of manuring fields with burned clay 
and the fertility of ferruginous soils, which have been 
considered as facts so incomprehensible, may be ex- 
plained in an equally simple manner. They have been 
ascribed to the great attraction for water, exerted by 
dry clay and ferruginous earth ; but common dry arable 
land possesses this property in as great a degree : and 
besides, what influence can be ascribed to a hundred 
pounds of water spread over an acre of land, in a con- 
dition in which it cannot be serviceable either by the 
roots or leaves ? The true cause is this : — 

Uiea, .... 
Hippnrate of soda, 
Sails and water, . 

1000 " 
* Boussingault, ^nn. de Chim. et de P/njs. t. Ixiii. p. 243. 



7 


parts. 


24 


<( 


. 979 


>( 



OF THE NITROGEN OF PLANTS. 145 

The oxides of iron and alumina are distinguished 
from all other metallic oxides by their power of forming 
solid compounds with ammonia. The precipitates ob- 
tained by the addition of ammonia to salts of alumina or 
iron are true salts, in which the ammonia is contained as 
a base. Minerals containing alumina or oxide of iron 
also possess, in an eminent degree, the remarkable 
property of attracting ammonia from the atmosphere 
and of retaining it. Vauquelin^ whilst engaged in the 
trial of a criminal case, discovered that all the rust of 
iron contains a certain quantity of ammonia. * Chevalier 
afterwards found that ammonia is a constituent of all 
minerals containing iron ; that even hematite, a mineral 
which is not at all porous, contains one per cent, of it. 
Bonis showed also, that the peculiar odor observed on 
moistening minerals containing alumina, is partly owing 
to their exhaling ammonia. Indeed, gypsum and some 
varieties of alumina, pipe-clay for example, emit so 
much ammonia, when moistened with caustic potash,, 
that even after they have been exposed for two days, lit- 
mus paper held over them becomes blue. Soils, there- 
fore, which contain oxides of iron, and burned clay,, 
must absorb ammonia, an action which is favored by 
their porous condition ; they further prevent the escape 
of the ammonia once absorbed, by their chemical prop- 
erties. Such soils, in fact, act precisely as a mineral 
acid would do, if extensively spread over their surface ; 
with this difference, that the acid would penetrate the 
ground, enter into combination with lime, alumina, and 
other bases, and thus lose, in a few hours, its property 
of absorbing ammonia from the atmosphere. 

The ammonia absorbed by the clay or ferruginous ox- 
13 



146 SOURCE OF THE NITROGEN OF PLANTS. 

ides is separated by every shower of rain, and conveyed 
in solution to the soil. 

Powdered charcoal possesses a similar action, but 
surpasses all other substances in the power which it pos- 
sesses of condensing ammonia within its pores, particu- 
larly when it has been previously heated to redness. 
Charcoal absorbs 90 times its volume of ammoniacal 
gas, which may be again separated by simply moistening 
it with water (De Saussure). Decayed wood approach- 
es very nearly to charcoal in this power ; decayed oak 
wood absorbs 72 times its volume, after having been 
completely dried under the air-pump. We have here 
an easy and satisfactory means of explaining still further 
the properties of humus, or wood in a decaying stale. 
It is not only a slow and constant source of carbonic 
acid, but it is also a means by which the necessary nitro- 
gen is conveyed to plants. 

Nitrogen is found in lichens, which grow on basaltic 
rocks. Our fields produce more of it than we have 
given them as manure, and it exists in all kinds of soils 
and minerals which were never in contact with organic 
substances. The nitrogen in these cases could only 
have been extracted from the atmosphere. 

We find this nitrogen in the atmosphere in rain-water 
and in alt kinds of soils, in the form of ammonia, as a 
product of the decay and putrefaction of preceding gen- 
erations of animals and vegetables. We find, likewise, 
that the proportion of azotized matters in plants is aug- 
mented by giving them a larger supply of ammonia con- 
veyed in the form of animal manure. 

No conclusion can then have a better foundation than 
this, that it is the ammonia of the atmosphere which fur- 
nishes nitrogen to plants. 



OF THE INORGANIC CONSTITUENTS OF PLANTS. 147 

Carbonic acid, water and ammonia, contain the ele- 
ments necessary for the support of animals and vegeta- 
bles. The same substances are the ultimate products of 
the chemical processes of decay and putrefaction. All 
the innumerable products of vitality resume, after death, 
the original form from which they sprung. And thus 
death, — the complete dissolution of an existing gener- 
ation, — becomes the source of life for a new one. 

But another question arises, — Are the conditions al- 
ready considered the only ones necessary for the life of 
vegetables ? It will now be shown that they are not. 



CHAPTER VI. 

OP THE INORGANIC CONSTITUENTS OF PLANTS. 

Carbonic acid, water and ammonia, are necessary 
for the existence of plants, because they contain the ele- 
ments from which their organs are formed ; but other sub- 
stances are likewise requisite for the formation of certain 
organs destined for special functions peculiar to each 
family of plants. Plants obtain these substances from 
inorganic nature. In the ashes left after the incineration 
of plants, the same substances are found, although in a 
changed condition. 

Many of these inorganic constituents vary according 
to the soil in which the plants grow, but a certain num- 
ber of them are indispensable to their development. 

All substances in solution in a soil are absorbed by 
the roots of plants, exactly as .a sponge imbibes a liquid. 



148 OF THE INORGANIC 

and all that it contains, without selection. The sub- 
stances thus conveyed to plants are retained in greater 
or less quantity, or are entirely separated when not suited 
for assimilation. 

Phosphate of magnesia in combination with ammonia 
is an invariable constituent of the seeds of all kinds of 
grasses. It is contained in the outer horny husk, and 
is introduced into bread along with the flour, and also 
into beer. The bran of flour contains the greatest 
quantity of it. It is this salt which forms large crys- 
talline concretions, often amounting to several pounds in 
weight, in the ccBCum of horses belonging to millers ; and 
when ammonia is mixed with beer, the same salt sepa- 
rates as a white precipitate. 

Most plants, perhaps all of them, contain organic acids 
of very different composition and properties, all of which 
are in combination with bases, such as potash, soda, lime 
or magnesia. These bases evidently regulate the for- 
mation of the acids, for the diminution of the one is 
followed by a decrease of the other : thus, in the grape, 
for example, the quantity of potash contained in its juice 
is less, when it is ripe, than when unripe ; and the acids, 
under the same circumstances, are found to vary in a 
similar manner. Such constituents exist in small quan- 
tity in those parts of a plant in which the process of 
assimilation is most active, as in the mass of woody fibre; 
and their quantity is greater in those organs, whose office 
it is to prepare substances conveyed to them for assimi- 
lation by other parts. The leaves contain more inor- 
ganic matters than the branches, and the branches more 
than the stem. The potato plant contains more potash 
before blossoming than after it. 

The acids found in the different families of plants are 



CONSTITUENTS OF PLANTS. 149 

of various kinds ; it cannot be supposed that their pres- 
ence and peculiarities are the result of accident. The 
fumaric and oxalic acids in the liverwort, the kinovic 
acid in the China nova, the rocellic acid in the Rocella 
tinctoria, the tartaric acid in grapes, and the numerous 
other organic acids, must serve some end in vegetable 
life. But if these acids constantly exist in vegetables, 
and are necessary to their life, which is incontestable, 
it is equally certain that some alkaline base is also indis- 
pensable in order to enter into combination w^ith the 
acids which are always found in the state of salts. All 
plants yield by incineration ashes containing carbonic 
acid ; all therefore must contain salts of an organic 
acid. 

Now, as we know the capacity of saturation of organic 
acids to be unchanging, it follows that the quantity of the 
bases united with them cannot vary, and for this reason 
the latter substances ought to be considered with the 
strictest attention both by the agriculturist and physi- 
ologist. 

We have no reason to believe that a plant in a con- 
dition of free and unimpeded growth produces more of 
its peculiar acids than it requires for its own existence ; 
hence, a plant, on whatever soil it grows, must contain 
an invariable quantity of alkaline bases. Culture alone 
will be able to cause a deviation. 

In order to understand this subject clearly, it will be 
necessary to bear in mind, that any one of the alkaline 
bases may be substituted for another, the action of all 
being the same. Our conclusion is, therefore, by no 
means endangered by the existence of a particular alkali 
in one plant, which may be absent in others of the same 
species. If this inference be correct, the absent alkali 
13* 



150 OF THE INORGANIC 

or earth must be supplied by one similar in its mode 
of action, or in other words, by an equivalent of another 
base. The number of equivalents of these various bases, 
which may be combined with a certain portion of acid, 
must necessarily be the same, and, therefore, the amount 
of oxygen contained in them must remain unchanged, 
under all circumstances, and on whatever soil they 
grow. 

Of course, this argument refers only to those alkaline 
bases, which in the form of organic salts form constitu- 
ents of the plants. Now, these salts are preserved in 
the ashes of plants, as carbonates, the quantity of which 
can be easily ascertained. 

It has been distinctly shown by the analyses of De 
Saussure and Berthier, that the nature of a soil exer- 
cises a decided influence on the quantity of the different 
metallic oxides contained in the plants, which grow on 
it ; that magnesia, for example, was contained in the 
ashes of a pine-tree grown at Mont Breven, whilst it 
was absent from the ashes of a tree of the same species 
from Mont La Salle, and that even the proportion of 
lime and potash was very different. 

Hence it has been concluded (erroneously, I believe), 
that the presence of bases exercises no particular influ- 
ence upon the growth of plants ; but even were this 
view correct, it must be considered as a most remarkable 
accident, that these same analyses furnish proof for the 
very opposite opinion. For although the composition 
of the ashes of these pine-trees was so very different, 
they contained, according to the analysis of De Saussure, 
an equal number of equivalents of metallic oxides ; or 
what is the same thing, the quantity of oxygen contained 
in all the bases was in both cases the same. 



CONSTITUENTS OF PLANTS. 151 

100 parts of the ashes of the pine-tree from Mont 

Breven contained : — * 

Carbonate of Potash . 3.G0 Quantity of oxygen in the Potash 0.41 
" Lime . 46.34 " " " Lime 7.33 

" Magnesia 0.77 " " " Magnesia 1.27 

Sum of the carbonates 56.71 Sum of the oxygen in the bases 9.01 

100 parts of the ashes of the pine from Mont La Salle 

contained : — f 

Carbonate of Potash . 7.36 Quantity of oxygen in the Potash 0.85 
" Lime . 51.19 «' " " Lime 8.10 

" MagnesiaOO.no 

Sum of the carbonates 58.55 Sum of the oxygen in the bases 8.95 
The numbers 9.01 and 8.95 resemble each other as 
nearly as could be expected even in analyses made for 
the very purpose of ascertaining the fact above demon- 
strated which the analyst in this case had not in view. 

Let us now compare Berthier's analyses of the ashes 
of two fir-trees, one of which grew in Norway, the other 
in Allevard (departement de I'Isere). One contained 
50, the other 25 per cent, of soluble salts. A greater 
difference in the proportion of the alkaline bases could 
scarcely exist between two totally different plants, and 
yet even here, the quantity of oxygen in the bases of 
both was the same. 

100 parts of the ashes of fir-wood from Allevard con- 
tained according to Berlhier, {A7in. de Chim. et de 
Phys. t. xxxii. p. 248,) 

Potash and Soda 16.8 in which 3.42 parts must be oxygen. 

Lime . 295 " 8.20 

Magnesia . 3.2 " 1.20 « " 



49.5 12.82 



* 100 parts of this wood gave 1.187 aslies. 
t 100 parts of this wood gave 1.128 ashes. 



152 OF THE INORGANIC 

Only part of the potash and soda in these ashes was 
in combination with organic acids, the remainder was in 
the form of sulphates, phosphates, and chlorides. One 
hundred parts of the ashes contained 3.1 sulphuric acid, 
4.2 phosphoric acid, and 0.3 hydrochloric acid, which, 
together, neutralize a quantity of base containing 1.20 
oxygen. This number therefore must be subtracted 
from 12.82. The remainder 11.62 indicates the quan- 
tity of oxygen in the alkaline bases, combined with or- 
ganic acids, in the fir-wood of Allevard. 

The fir-wood of Norway contained in 100 parts : * 

Potash . 14.1 of which 2.4 parts would be oxygen. 

Soda . 20.7 " 5.3 " " 

Lime . 12.3 " 3.45 " " 

Magnesia . 4.35 " 1.G9 " " 

51.45 12.84 

And if the quantity of oxygen of the bases in combina- 
tion with sulphuric and phosphorip acid, viz. 1.37, be 
again subtracted from 12.84, 11.47 parts remain as the 
amount of oxygen contained in the bases, which were in 
combination with organic acids. 

These remarkable approximations cannot be acci- 
dental ; and if further examinations confirm them in 
other kinds of plants, no other explanation than that 
already given can be adopted. 

It is not known in what form silica, manganese, and 
oxide of iron, are contained in plants, but we are cer- 
tain that potash, soda, and magnesia, can be extracted 
from all parts of their structure in the form of salts of 

* This calculation is exact only in the case where the quantity of 
ashes is equal in weight for a given quantity of wood ; the difference 
cannot, however, be admitted to be so great as to change sensiblj' the 
above proportions. Berthier has not mentioned the proportion of 
ashes contained in the wood. — L. 



CONSTITUENTS OF PLANTS. 153 

organic acids. The same is the case with lime, when 
not present as insoluble oxalate of lime. It must here 
be remembered, that in plants yielding oxalic acid, the 
acid and potash never exist in the form of a neutral or 
quadruple salt, but always as a double acid salt, on 
whatever soil they may grow. The potash in grapes, 
also, is more frequently found as an acid salt, viz. cream 
of tartar, than in the form of a neutral compound. As 
these acids and bases are never absent from plants, and 
as even the form in which they present themselves is 
not subject to change, it may be affirmed, that they ex- 
ercise an important influence on the development of the 
fruits and seeds, and also on many other functions of the 
nature of which we are at present ignorant. 

The quantity of alkaline bases existing in a plant also 
depends evidently on this circumstance of their existing 
only in the form of acid salts, for the capacity of satura- 
tion of an acid is constant ; and when we see oxalate of 
lime in the lichens occupying the place of woody fibre, 
which is absent, we must regard it as certain, that the 
soluble organic salts are destined to fulfil equally impor- 
tant, though different functions, so much so, that we 
could not conceive the complete development of a 
plant without their presence, that is, without the pres- 
ence of their acids, and consequently of their bases. 

From these considerations we must perceive that ex- 
act and trustworthy examinations of the ashes of plants 
of the same kind growing upon different soils would be 
of the greatest importance to vegetable physiology, and 
would decide whether the facts above mentioned are the 
results of an unchanging law for each family of plants, 
and whether an invariable number can be found to ex- 
press the quantity of oxygen which each species of plant 
contains in the bases united with organic acids. In all 



154 OP THE INORGANIC 

probability, such inquiries will lead to most important 
results ; for it is clear, that if the production of a certain 
unchanging quantity of an organic acid is required by 
the peculiar nature of the organs of a plant, and is neces- 
sary to its existence, then potash or lime must be taken 
up by it, in order to form salts with this acid ; that if 
these do not exist in sufficient quantity in the soil, other 
bases must supply their place ; and that the progress of 
a plant must be wholly arrested when none are present. 

Seeds of the Salsola Kali, when sown in common 
garden soil, produce a plant containing both potash and 
soda ; while the plants grown from the seeds of this con- 
tain only salts of potash, with mere traces of muriate of 
soda. (Cadet.) 

The existence of vegetable alkalies in combination 
with organic acids gives great weight to the opinion, 
that alkaline bases in general are connected with the de- 
velopment of plants. 

If potatoes are grown where they are not supplied 
with earth, the magazine of inorganic bases, (in cellars 
for example,) a true alkali, called Solanin, of very poi- 
sonous nature, is formed in the sprouts which extend 
towards the light, while not the smallest trace of such a 
substance can be discovered in the roots, herbs, blos- 
soms, or fruits of potatoes grown in fields. (Otto).* 

* The analysis of potatoes afforded M. Henry 

Starch 13.3 

Water 73.12 

Albumen 0.92 

Uncrystallizable sugar ..... 3.30 

Volatile poisonous matter .... 0.05 

Peculiar fatty matter 1.12 

Parenchyma 6.79 

Malic acid and salts 1.40 

100.00 



CONSTITUENTS OF PLANTS. 155 

In all the species of the Cinchona, kinic acid is found ; 
but the quantity of quinina, cinchonina, and lime which 
they contain is most variable. From the fixed bases in 
the products of incineration, however, we may estimate 
pretty accurately the quantity of the peculiar organic 
bases. A maximum of the first corresponds to a mini- 
mum of the latter as must necessarily be the case if they 
mutually replace one another according to their equiva- 
lents. We know that different kinds of opium contain 
meconic acid, in combination with very difierent quan- 
tities of narcotina, morphia, codeia, &c., the quantity 
of one of these alkaloids diminishing on the increase of 
the others. " Thus, the smallest quantity of morphia 
is accompanied by a maximum of narcotina. Not a 
trace of meconic acid* can be discovered in many kinds 
of opium, but there is not on this account an absence of 
acid, for the meconic is here replaced by sulphuric acid. 
Here, also, we have an example of what has been before 
stated, for in those kinds of opium where both these 
acids exist, they are always found to bear a certain rela- 
tive proportion to one another. 

But if it be found, as appears to be the case in the 
juice of poppies, that an organic acid may be replaced 
by an inorganic, without impeding the growth of a plant, 
we must admit the probability of this substitution taking 
place in a much higher degree in the case of the inor- 
ganic bases. 

When roots find their more appropriate base in suffi- 
cient quantity, they will take up less of another. 

* Robiquet did not obtain a trace of meconate of lime from 300 lbs. 
of opium, whilst in other kinds the quanlit}' was very considerable. 
Ann. de Chim. liii. p. 4'-i5. — L. 



156 OP THE INORGANIC 

These phenomena do not show themselves so fre- 
quently in cultivated plants, because they are subjected 
to special external conditions for the purpose of the pro- 
duction of particular constituents or particular organs. 

When the soil, in which a wiiite hyacinth is growing 
in the state of blossom, is sprinkled with the juice of the 
Phytolaca decandra,* the white blossoms assume, in one 
or two hours, a red color, which again disappears after 
a few days under the influence of sunshine, and they be- 
come white and colorless as before f. The juice in 
this case evidently enters into all parts of the plant, 
without being at all changed in its chemical nature, or 
without its presence being apparently either necessary or 
injurious. But this condition is not permanent, and 
when the blossoms have become again colorless, none 
of the coloring matter remains ; and if it should occur, 
that any of its elenients were adapted for the purposes 
of nutrition of the j)lant, then these alone would be re- 
tained, whilst the rest would be excreted in an altered 
form by the roots. 

Exactly the same thing must happen when we sprin- 
kle a plant with a solution of chloride of potassium, 
nitre, or nitrate of strontia ; they will enter into the dif- 
ferent parts of the plant, just as the colored juice men- 
tioned above, and will be found in its ashes if it should 
be burnt at this period. Their presence is merely ac- 
cidental ; but no conclusion can be hence deduced 
against the necessity of the presence of other bases in 
plants. The experiments of Macaire-Princep have 



* American nightshade. 

t Biot, in the Comptes rendus des Seances dc VAcadhnie des Sci- 
ences, a Paris, ler Semestre, 1837. p. 12. 



CONSTITUENTS OF PLANTS. 157 

shown that plants made to vegetate with their roots in a 
weak sohjtion of acetate of lead (sugar of lead), and 
then in rain-water, yield to the latter all the salt of lead 
which they had previously absorbed. They return, 
therefore, to the soil all matters which are unnecessary 
to their existence. Again, when a plant, freely exposed 
to the atmosphere, rain, and sunshine, is sprinkled with 
a solution of nitrate of strontian, the salt is absorbed, 
but it is again separated by the roots and removed fur- 
ther from them by every shower of rain, which moistens 
the soil, so that at last not a trace of it is to,be found in 
the plant. 

Let us consider the composition of the ashes of two 
fir-trees as analyzed by an acute and most accurate 
chemist. One of these grew in Norway on a soil, the 
constituents of which never changed, but to which solu- 
ble salts, and particularly common salt, were conveyed 
in great quantity by rain-water. How did it happen 
that its ashes contained no appreciable trace of salt, 
although we are certain that its roots must have absorb- 
ed it after every shower '' 

We can explain the absence of salt in this case by 
means of the direct and positive observations referred 
to, which have shown that plants have the power of re- 
turning to the soil all substances unnecessary to their 
existence ; and the conclusion to which all the fore- 
going facts lead us, when their real value and bearing 
are apprehended, is that the alkaline bases existing in 
the ashes of plants must be necessary to their growth, 
since if this were not the case they would not be re- 
tained. 

The perfect development of a plant according to 
this view is dependent on the presence of alkalies or 
14 



158 OF THE INORGANIC 

alkaline earths ; for when these substances are totally 
wanting, its growth will be arrested, and when they are 
only deficient, it must be impeded. 

In order to apply these remarks, let us compare two 
kinds of tree, the wood of which contains unequal 
quantities of alkaline bases, and we shall find that one of 
these grows luxuriantly in several soils, upon which the 
others are scarcely able to vegetate. For example, 
10,000 parts of oak wood yield 250 parts of ashes, the 
same quantity of fir-wood only 83, of linden -wood 500, 
of rye 440, and of the herb of the potato-plant 1500 
parts.* 

Firs and pines find a sufficient quantity of alkalies in 
granitic and barren sandy soils, in which oaks will not 
grow ; and wheat thrives in soils favorable for the 
linden-tree, because the bases, which are necessary to 
bring it to complete maturity, exist there in sufficient 
quantity. The accuracy of these conclusions, so highly 
important to agriculture and to the cultivation of forests, 
can be proved by the most evident facts. 

All kinds of grasses, the Erjuisetacece, for example, 
contain in the outer parts of their leaves and stalk a 
large quantity of silicic acid and potash, in the form of 
acid silicate of potash. The proportion of this salt 
does not vary perceptibly in the soil of corn-fields, be- 
cause it is again conveyed to them as manure in the 
form of putrefying straw. But this is not the case in a 
meadow, and hence we never find a luxuriant crop of 
grass f on sandy and calcareous soils which contain 

* Berthier, Annales de Chiviie et de Physique, tome xxx. p. 248. 

t It would be of importance to examine what alkalies are contained 
in the ashes of the sea-shore plants whicii grow in the humid hollows 
of downs, and especially in those of the millet-grass. {Hartig.) If 



CONSTITUENTS OF PLANTS. 159 

liltle potash, evidently because one of the constituents 
indispensable to the growth of the plants is wanting. 
Soils formed from basalt, grauwacke, and porphyry are, 
cceteris paribus, the best for meadow land, on account 
of the quantity of potash which enters into their compo- 
sition. The potash abstracted by the plants is restored 
during the annual irrigation.* That contained in the 
soil itself is inexhaustible in comparison w^ith the quan- 
tity removed by plants. 

But when we increase the crop of grass in a meadow 
by means of gypsum, we remove a greater quantity of 
potash with the hay than can, under the same circum- 
stances, be restored. Hence it happens, that after the 
lapse of several years, the crops of grass on the mead- 
ows manured with gypsum diminish, owing to the defi- 
ciency of potash. But if the meadow be strewed from 
time to time with wood-ashes, even w'ith the lixiviated 
ashes which have been used by soap-boilers, (in Ger- 
many much soap is made from the ashes of wood,) then 
the grass thrives as luxuriantly as before. The ashes 
are only a means of restoring the potash. f 

potash is not found in them it must certainly be replaced bj soda as 
in the salsola, or by lime as in the Plumhaginea. — L. 

* A very high value is attached in Germany to the cultivation of 
orrass as winter provision for cattle, and the greatest care is used in 
order to obtain the greatest possible quantity. In the vicinity of 
Liegen (a town in Nassau), from three to five perfect crops are ob- 
tained from one meadow, and this is effected by covering the fields 
with river-water, which is conducted over the meadow in spring by 
numerous small canals. This is found to be of such advantage, that 
supposing a meadow not so treated to yield 1,000 lbs. of hay, then 
from one thus watered 4,500 lbs. are produced. In respect to the 
cultivation of meadows, the country around Liegen is considered to 
be the best in all Germany. — L. 

t The compost which has been employed with most advantage as 



160 OF THE INORGANIC 

A harvest of grain is obtained every thirty or forty 
years from the soil of the Ltineburg heath, by strewing 
it with the ashes of the heath-plants (Erica vulgaris) 
which grow on it. These plants during the long period 
just mentioned collect the potash and soda, which are 
conveyed to them by rain-water ; and it is by means of 
these alkalies, that oats, barley, and rye, to which they 
are indispensable, are enabled to grow on this sandy 
heath. 

The woodcutters in the vicinity of Heidelberg have 
the privilege of cultivating the soil for their own use, 
after felling the trees used for making tan. Before sow- 
ing the land thus obtained, the branches, roots, and 
leaves are in every case burned, and the ashes used as 
a manure, which is found to be quite indispensable for 
the growth of the grain. The soil itself, upon which 
the oats grow in this district, consists of sandstone ; and 
although the trees find in it a quantity of alkaline earths 
sufficient for their own sustenance, yet in its ordinary 
condition it is incapable of producing grain. 

a top dressing to grass by Mr., Haggerston, on the estate of J. P. 
Gushing, Esq., at Watertown, is prepared from peat and barilla alone. 

The peat previously cut and dried is made into heaps with alter- 
nate layers of barilla, the thickness of each layer of peat being 
eight inches, and of the barilla four inches. This heap is allowed to 
remain undisturbed during the winter, in the spring it is carefully 
turned and then allowed to remain until the ensuing autumn, when 
it is spread upon the land. 

Peat which is to be ploughed into the land, having been deposited 
in the yard to whicii swine have free access, is mixed with stable 
manure in the proportion of two thirds peat to one third manure. 

Barilla is the crude soda which is imported from Spain, Sicily, &c., 
where it is prepared by burning the plant called salsola soda. Ac- 
cording to Dr. Ure it contains iJO per cent, of real alkali (soda) with 
muriates and sulphates of soda, some lime and alumina, with very 
little sulphur. 



CONSTITUENTS OF PLANTS. 161 

The most decisive proof of the use of strong manure 
was obtained at Bingen (a town on the Rhine), where 
the produce and development of vines were highly in- 
creased by manuring them with such substances as 
shavings of horn, &c., but after some years the forma- 
tion of the wood and leaves decreased to the great loss 
of the possessor, to such a degree, that he has long had 
cause to regret his departure from the usual methods. 
By the manure employed by him, the vines had been 
too much hastened in their growth ; in two or three 
years they had exhausted the potash in the formation of 
their fruit, leaves, and wood, so that none remained for 
the future crops, his manure not having contained any 
potash. 

There are vineyards on the Rhine, the plants of 
which are above a hundred years old, and all of these 
have been cultivated by manuring them with cow-dung, 
a manure containing a large proportion of potash, al- 
though very little nitrogen. All the potash, in fact, 
which is contained in the food consumed by a cow is 
again immediately discharged in its excrements. 

The experience of a proprietor of land in the vicinity 
of Gottingen offers a most remarkable example of the 
incapability of a soil to produce wheat or grasses in gen- 
eral, when it fails in any one of the materials necessary 
to their growth. In order to obtain potash, he planted 
his whole land with wormwood, the ashes of which are 
well known to contain a large proportion of the carbo- 
nate of that alkali. The consequence was, that he ren- 
dered his land quite incapable of bearing grain for many 
years, in consequence of having entirely deprived the 
soil of its potash. 

The leaves and small branches of trees contain the 
14* 



162 OF THE INORGANIC 

most potash ; and the quantity of them which is annually- 
taken from a wood, for tiie purpose of being employed 
as litter,* contain more of that alkali than all the old 
wood which is cut down. The bark and foilage of 
oaks, for example, contain from 6 to 9 per cent, of this 
alkali ; the needles of firs and pines 8 per cent. 

With every 2,650 lbs. of fir-wood, which are yearly 
removed from an acre of forest, only from 0.114 to 
0.53 lbs. of alkalies are abstracted from the soil, calcu- 
lating the ashes at 0.S3 per cent. The moss, however, 
which covers the ground, and of which the ashes are 
known to contain so much alkali, continues uninterrupt- 
ed in its growth, and retains that potash on the surface, 
which would otherwise so easily penetrate with the rain 
through the sandy soil. By its decay, an abundant 
provision of alkalies is supplied to the roots of the trees, 
and a fresh supply is rendered unnecessary. 

The supposition of alkalies, metallic oxides, or inor- 
ganic matter in general, being produced by plants, is en- 
tirely refuted by these well authenticated facts. 

It is thought very remarkable, that those plants of the 
grass tribe, the seeds of which furnish food for man, fol- 
low him like the domestic animals. But saline plants 
seek the sea-shore or saline springs, and the Chenopo- 
dium the dunghill from similar causes. Saline plants 
require common salt, and the plants which grow only on 



* [This refers to a custom some time since very prevalent in Ger- 
many, although now discontinued. The leaves and small twigs of 
trees were gleaned from the forests by poor people, for the purpose of 
beintr used as litter for their cattle. The trees, however, were found to 
suffer so much in consequence, that a strict prohibition is now placed 
acrainst their removal. The cause of the injury was that stated in the 
text. — Trans.] 



CONSTITUENTS OF PLANTS. 163 

dunghills, need ammonia and nitrates, and they are at- 
tracted whither these can be found, just as the dung-fly 
is to animal excrements. So likewise none of our corn 
plants can bear perfect seeds, that is, seeds yielding 
flour, without a large supply of phosphate of magnesia 
and ammonia, substances which they require for their 
maturity. And hence, these plants grow only in a soil 
where these three constituents are found combined, and 
no soil is richer in them, than those where men and ani- 
mals dwell together ; where the urine and excrements 
of these are found corn plants appear, because their 
seeds cannot attain maturity unless supplied with the 
constituents of those matters. 

When we find sea plants near our salt works, several 
hundred miles, distant from the sea, we know that their 
seeds have been carried there in a very natural manner, 
namely, by wind or birds, which have spread them over 
the whole surface of the earth, although they grow only 
in those places in which they find the conditions essen- 
tial to their life. 

Numerous small fish, of not more than two inches in 
length (^G asterosteus aculeatus), are found in the salt- 
pans of the graduating house at Nidda (a village in 
Hesse Darmstadt). No living animal is found in the 
salt-pans of Neuheim, situated about 18 miles from Nid- 
da ; but the water there contains so much carbonic acid 
and lime, that the walls of the graduating house are cov- 
ered with stalactites. Hence the eggs conveyed to this 
place by birds do not find the conditions necessary for 
their development, which they found in the former 
place.* 

* " The itch insect (Icarus Scabiei) is considered by Burdach as the 



164 OF THE INORGANIC 

How much more wonderful and inexplicable does it 
appear, that bodies which remain fixed in the strong heat 
of a fire, have under certain conditions the property of 
volatilizing, and, at ordinary temperatures, of passing 
into a state, of which we cannot say whether they have 
really assumed the form of a gas or are dissolved in 
one ! Steam or vapors in general have a very singular 
influence in causing the volatilization of these bodies, 
that is, of causing them to assume the gaseous form. A 
liquid during evaporation communicates the power of as- 
suming the same state in a greater or less degree to all 
substances dissolved in it, although they do not of them- 
selves possess that property. 

Boracic acid * is a substance which is completely fixed 
in the fire ; it suffers no change of weight appreciable 
by the most delicate balance, when exposed to a white 
heat, and, therefore, it is not volatile. Yet its solution 
in water cannot be evaporated by the gentlest heat, with- 



production of a morbid condition, so likewise lice in children; the 
original generation of the fresh water muscle (mytilus) in fish ponds, 
of sea plants in the vicinity of salt works, of nettles and grasses, of 
fish in pools of rain, of trout in mountain streams, &c., is according 
to the same natural philosopher not impossible." A soil consisting of 
crumbled rocks, decayed vegetables, rain and salt water, &c., is here 
supposed to possess the power of generating shell fish, trout, and salt- 
worts (saUcornia). All inquiry is arrested by such opinions, when 
propagated by a teacher who enjoys a merited reputation, obtained by 
knowledge and hard labor. These subjects, however, have hitherto 
met with the most superficial observation, although they well merit 
strict investigation. The dark, the secret, the mysterious, the enigr 
malic, is, in fact, too seducing for the youthful and philosophic mind, 
which would penetrate the deepest depths of nature, without the as- 
sistance of the shaft or ladder of the miner. This is poetry, but not 
sober philosophical inquiry. — L. 
* The acid from borax. 



CONSTITUENTS OF PLANTS. 165 

out the escape of a sensible quantity of the acid with 
the steam. Hence it is that a loss is always experi- 
enced in the analysis of minerals containing this acid, 
when liquids in which it is dissolved are evaporated. 
The quantity of boracic acid which escapes with a cubic 
foot of steam, at the temperature of boiling water, can- 
not be detected by our most sensible reagents ; and 
nevertheless the many hundred tons annually brought 
from Italy as an article of commerce, are procured by 
the uninterrupted accumulation of this apparently inap- 
preciable quantity. The hot steam which issues from 
the interior of the earth is allowed to pass through cold 
water in the lagoons of Castel Nuovo and Cherchiago ; 
in this way is the boracic acid gradually accumulated, till 
at last it may be obtained in crystals by the evaporation 
of the water. It is evident, from the temperature of the 
steam, that it must have come out of depths in which 
human beings and animals never could have lived, and 
yet it is very remarkable and highly important that am- 
monia is never absent from it. In the large works in 
Liverpool, where natural boracic acid is converted into 
borax, many hundred pounds of sulphate of ammonia 
are obtained at the same time. 

This ammonia has not been produced by the animal 
organism, it existed before the creation of human beings; 
it is a part^ a primary constituent, of the globe itself. 

The experiments instituted under .Lavoisier^s guid- 
ance by the Direction des poudres et salpetres, have 
proved that during the evaporation of the saltpetre ley, 
the salt volatilizes with the water, and causes a loss 
which could not before be explained. It is known also, 
that, in sea storms, leaves of plants in the direction of 
the wind are covered with crystals of salt, even at the 



166 OF THE INOftGANlC 

distance of from 20 to 30 miles from the sea. But it 
does not require a storm to cause the volatilization of the 
salt, for the air hanging over the sea always contains 
enough of this substance to make a solution of nitrate of 
silver turbid, and every breeze must carry this away. 
Now, as thousands of tons of sea-water annually evapo- 
rate into the atmosphere, a corresponding quantity of the 
salts dissolved in it, viz. of common salt, chloride of 
potassium, magnesia, and the remaining constituents of 
the sea-water will be conveyed by wind to the land. 

This volatilization is a source of considerable loss in 
salt-works, especially where the proportion of salt in the 
water is not large. This has been completely proved 
at the salt-works of Nauheim, by the very intelligent 
director of that establishment, JM. Wilhelmi. He hung 
a plate of glass between two evaporating houses, which 
were about 1200 paces distant from each other, and 
found in the morning, after the drying of the dew, that 
the glass was covered with crystals of salt on one or the 
other side, according to the direction of the wind. 

By the continual evaporation of the sea, its salts * are 
spread over the whole surface of the earth ; and being 
subsequently carried down by the rain, furnish to the 
vegetation those salts necessary to its existence. This 
is the origin of the salts found in the ashes of plants, 
in those cases where the soil could not have yielded 
them. 

* According to Marcet, sea- water contains in 1000 parts, 
2G.6GC Chloride of Sodium. 
4.CC0 Sulpliate of Soda. 
1.232 Ciiloride of Potassium. 
5.152 Chloride of Magnesium. 
1.5 Sulphate of Lime. 



CONSTITUENTS OF PLANTS. 167 

In a comprehensive view of the phenomena of nature, 
we have no scale for that w^hich we are accustomed to 
name, small or great ; all our ideas are proportioned to 
what we see around us, but how insignificant are they in 
comparison with the whole mass of the globe ! that 
which is scarcely observable in a confined district ap- 
pears inconceivably large when regarded in its extension 
through unlimited space. The- atmosphere contains only 
a thousandth part of its weight of carbonic acid ; and 
yet small as this proportion appears, it is quite sufficient 
to supply the whole of the present generation of living 
beings with carbon for a thousand years, even if it were 
not renewed. Sea-water contains -j-23^0 o ^^ '^s weight 
of carbonate of lime ; and this quantity, although scarcely 
appreciable in a pound, is the source from which myriads 
of marine mollusca and corals are supplied with materials 
for their habitations. 

Whilst the air contains only from 4 to 6 ten-thousandth 
parts of its volume of carbonic acid, sea-water contains 
100 times more (10,000 volumes of sea-water contain 
620 volumes of carbonic acid, — Laurent, Bouillon, 
Lagrange). Ammonia* is also found in this water, 
so that the same conditions which sustain living beings 
on the land are combined in this medium, in which a 
whole world of other plants and animals exist. 

The roots of plants are constantly engaged in collect- 
ing from the rain those alkalies which formed part of the 
sea-vvaier, and also those of the water of springs, which 
penetrates the soil. Without alkalies and alkaline bases 



* When the solid saline residue obtained by the evaporation of sea- 
water is heated in a retort to redness, a sublimate of sal-ammoniac is 
obtained. — Marcet. 



168 OF THE INORGANIC CONSTITUENTS OF PLANTS. 

most plants could not exist, and without plants the alka- 
lies would disappear gradually from the surface of the 
earth , 

When it is considered, that sea-water contains less 
than one-millionth of its own weight of iodine,* and that 
all combinations of iodine with the metallic bases of 
alkalies are highly soluble in water, some provision must 
necessarily be supposed to exist in the organization of 
sea-weed and the different kinds of Fuci, by which they 
are enabled during their life to extract iodine in the form 
of a soluble salt from sea-water, and to assimilate it in 
such a manner, that it is not again restored to the sur- 
rounding medium. These plants are collectors of iodine, 
just as land-plants are of alkalies ; and they yield us this 
element, in quantities such as we could not otherwise 
obtain from the water without the evaporation of whole 
seas. 

We take it for granted, that the sea plants require 
metallic iodides for their growth, and that their existence 
is dependent on the presence of those substances. With 
equal justice, then, we conclude, that the alkalies and 
alkaline earths, always found in the ashes of land-plants, 
are likewise necessary for their development. 

* This substance was discovered in 1812, and is obtained from 
marine plants ; it is found also in sea-water and several mineral 
springs in combination with hydrogen as hydriodic acid. With bases 
this acid forms hydriodates. Iodine has not been decomposed. It is 
a solid and at about 350" F. passes into vapor of a beautiful violet 
color; hence its name. 



THE ART OF CULTURE. 169 

CHAPTER VII. 

THE ART OF CULTURE. 

The conditions necessary for the life of all vegetables 
have been considered in the preceding part of the work. 
Carbonic acid, ammonia, and water yield elements for 
all the organs of plants. Certain inorganic substances, — 
salts and metallic oxides, — serve peculiar functions in 
their organism, and many of them must be viewed as 
essential constituents of particular parts. 

The atmosphere and the soil offer the same kind of 
nourishment to the leaves and roots. The former con- 
tains a comparatively inexhaustible supply of carbonic 
acid and ammomia ; the latter, by means of its humus, 
generates constantly fresh carbonic acid, whilst, during 
the winter, rain and snow introduce into the soil a 
quantity of ammonia, sufficient for the development of 
the leaves and blossoms. 

The complete, or it may be said, the absolute insol- 
ubility in cold water of vegetable matter in progress of 
decay, (humus,) appears on closer consideration to be 
a most wise arrangement of nature. For if humus pos- 
sessed even a smaller degree of solubility, than that 
ascribed to the substance called humic acid, it must be 
dissolved by rain-water. Thus, the yearly irrigation of 
meadows (see note at page 159), which lasts for several 
weeks, would remove a great part of it from the ground, 
and a heavy and continued rain would impoverish a soil. 
But it is soluble only wiien combined with oxygen -, 
it can be taken up by water, therefore, only as carbonic 
acid. 

15 



170 THE ART OF CULTURE. 

When kept in a dry place, humus may be preserved 
for centuries, but when moistened with water, it converts 
the surrounding oxygen into carbonic acid. As soon as 
the action of the air ceases, that is, as soon as it is de- 
prived of oxygen, the humus suffers no further change. 
Its decay proceeds only when plants grow in the soil 
containing it ; for they absorb by their roots the carbonic 
acid as it is formed. Their soil receives again from liv- 
ing plants the carbonaceous matter it thus loses, so that 
the proportion of humus in it does not decrease. 

The stalactitic caverns in Franconia, and those in the 
vicinity of Baireuth, and Streitberg, lie beneath a fertile 
arable soil ; the abundant decaying vegetables or humus 
in this soil, being acted on by moisture and air, constant- 
ly evolve carbonic acid, which is dissolved by the rain. 
The rain-water thus impregnated permeates the porous 
limestone, which forms the walls and roofs of the cav- 
erns, and dissolves in its passage as much carbonate of 
lime as corresponds to the quantity of carbonic acid con- 
tained in it. Water and the excess of carbonic acid 
evaporate from this solution when it has reached the in- 
terior of the caverns, and the limestone is deposited on ■ 
the walls and roofs in crystalline crusts of various forms- 
There are few spots on the earth where so many circum- 
stances favorable to the production of humate of lime 
are combined, if the humus actually existed in the soil in 
the form of humic acid. Decaying vegetable matter, 
water, and lime in solution, are brought together, but 
the stalactites formed contain no trace of vegetable mat- 
ter, and no humic acid ; they are of glistening white or 
yellowish color, and in part transparent, like calcareous 
spar, and may be heated to redness without becoming 
black. 



USE OF THE HUMUS, 171 

The subterranean vaults in the old castles near the 
Rhine, the " Bergstrasse " and Wetherau, are con- 
structed of sandstone, granite, or basalt, and present ap- 
pearances similar to the limestone caverns. The roofs 
of these vaults or cellars are covered externally to the 
thickness of several feet with vegetable mould, which 
has been formed by the decay of plants. The rain fall- 
ing upon them sinks through the earth, and dissolves the 
mortar by means of the carbonic acid derived from the 
mould ; and this solution evaporating in the interior of 
the vaults, covers them with small thin stalactites, which 
are quite free from humic acid. 

In such a filtering apparatus, built by the hand of 
nature, we have placed before us experiments which have 
been continued for a hundred or a thousand years. Now, 
if water possesses the power of dissolving a hundred- 
thousandth part of its own weight of humic acid or hu- 
mate of lime, and humic acid were present, we should 
find the inner surface of the roofs of these vaults and 
caverns covered with these substances ; but we cannot 
detect the smallest trace of them. There could scarcely 
be found a more clear and convincing proof of the ab- 
sence of the humic acid of chemists in common vegeta- 
ble mould. 

The common view, which has been adopted respect- 
ing the modus operandi of humic acid, has given occasion 
to the following inexplicable phenomenon: — A very 
small quantity of humic acid dissolved in water gives it 
a yellow or brown color. Hence it would be supposed, 
that a soil would be more fruitful in proportion as it was 
capable of giving this color to water, that is, of yielding 
it humic acid. But it is very remarkable that plants do 
not thrive in such a soil, and that all manure must have 
lost this property before it can exercise a favorable in- 



172 THE ART OF CULTURE. 

fluence upon their vegetation. Water from barren peat 
soils and marshy meadows, upon which few plants flour- 
ish, contains much of this humic acid ; but all agricul- 
turists and gardeners agree that the most suitable and best 
manure for plants is that which has completely lost the 
property of giving a color to water.* 

The soluble substance, which gives to water a brown 
color, is a product of the putrefaction of all animal and 
vegetable matters ; its formation is an evidence, that 
there is not oxygen sufficient to begin or at least to com- 
plete the decay. The brown solutions, containing this 
substance, are decolorized in the air, by absorbing oxy- 
gen, and a black coaly matter precipitates, — the sub- 
stance named "coal of humus." Now if a soil were 
impregnated with this matter, the effect on the roots of 
plants would be the same as that of entirely depriving the 
soil of oxygen ; plants would as little be able to grow in 
such ground, as they would if hydrated protoxide of '.oA 
were mixed with the soil. All plants die in soils and 
water which contain no oxygen ; absence of air acts ex- 
actly in the same manner as an excess of carbonic acid. 
Stagnant water on a marshy soil excludes air, but a re- 
newal of water has the same effect as a renewal of air, 
because water contains it in solution. If the water is 
withdrawn from a marsh, free access is given to the air, 
and the marsh is changed into a fruitful meadow. 

In a soil to which the air has no access, or at most 
but very little, the remains of animals and vegetables do 
not decay, for they can only do so when freely supplied 
with oxygen ; but they undergo putrefaction, for which 
air is present in sufficient quantity. Putrefaction is 
known to be a most powerful deoxidizing process, the 

* See Appendix. 



USE OF THE HUMUS. 173 

influence of which extends to all surrounding bodies, 
even to the roots and the plants themselves. All sub- 
stances from which oxygen can be extracted yield it to 
putrefying bodies ; yellow oxide of iron passes into the 
state of black oxide, sulphate of iron into sulphuret of 
iron, &c. 

The frequent renewal of air by ploughing, and the 
preparation of the soil, especially its contact with alka- 
line metallic oxides, the ashes of brown coal, burnt lime 
or limestone, change the putrefaction of its organic con- 
stituents into a pure process of oxidation ; and from the 
moment at which all the organic matter existing in a soil 
enters into a state of oxidation or decay, its fertility is 
increased. The oxygen is no longer employed for the 
conversion of the brown soluble matter into the insoluble 
coal of humus, but serves for the formation of carbonic 
acid. This change takes place very slowly, and, in some 
instances, the oxygen is completely excluded by it. And, 
whenever this happens, the soil loses its fertility. Thus, 
in the vicinity of Salzhausen (a village in Hesse Darm- 
stadt, famed for its mineral springs), upon a meadow 
called Griinschwalheimer, unfruitful spots are seen here 
and there covered with a yellow grass. If a hole be 
bored from 20 to 25 feet deep in one of these spots, 
carbonic acid is emitted from it with such violence, that 
the noise made by the escape of the gas may be distinctly 
heard at the distance of several feet. Here the carbonic 
acid rising to the surface displaces completely all the air, 
and consequently all the oxygen, from the soil ; and without 
oxygen, neither seeds nor roots can be developed ; a 
plant will not vegetate in pure nitrogen or carbonic acid 
gas.* 

* See note pao-e 119. 

15* 



174 THE ART OF CULTURE. 

Humus supplies young plants with nourishment by the 
roots, until their leaves are matured sufficiently to act as 
exterior organs of nutrition ; its quantity heightens the 
fertility of a soil by yielding more nourishment in this 
first period of growth, and consequently by increasing 
the number of organs of atmospheric nutrition. Those 
plants, which receive their first food from the substance 
of their seeds, such as bulbous plants, could completely 
dispense with humus ; its presence is useful only in so 
far as it increases and accelerates their development, but 
it is not necessary, — indeed, an excess of it at the com- 
mencement of their growth is, in a certain measure, in- 
jurious. 

The amount of food which young plants can take from 
the atmosphere in the form of carbonic acid and ammonia 
is limited ; they cannot assimilate more than the air con- 
tains. Now, if the quantity of their stems, leaves, and 
branches has been increased by the excess of food yield- 
ed by the soil at the commencement of their develop- 
ment, they will require for the completion of their growth, 
and for the formation of their blossoms and fruits, more 
nourishment from the air than it can aflx)rd, and conse- 
quently they will not reach maturity. In many cases the 
nourishment afforded by the air under these circumstan- 
ces suffices only to complete the formation of the leaves, 
stems, and branches. The same result then ensues as 
when ornamental plants are transplanted from the pots in 
which they have grown to larger ones, in which their 
roots are permitted to increase and multiply. All their 
nourishment is employed for the increase of their roots 
and leaves ; they spring, as it is said, into an herb or 
weed, but do not blossom. When, on the contrary, we 
take away part of the branches, and of course their 



NUTRITION AND GROWTH OF PLANTS. 175 

leaves with them, from dwarf trees, since we thus pre- 
vent the development of new branches, an excess of 
nutriment is artificially procured for the trees, and is em- 
ployed by them in the increase of the blossoms and en- 
largement of the fruit. It is to effect this purpose that 
vines are pruned. 

A new and peculiar process of vegetation ensues in all 
perennial plants, such as shrubs, fruit and forest trees, 
after the complete maturity of their fruit. The stem of 
annual plants, at this period of their growth, becomes 
woody, and their leaves change in color. The leaves of 
trees and shrubs on the contrary remain in activity until 
the commencement of the winter. The formation of the 
layers of wood progresses, the wood becomes harder and 
more solid, but after August the leaves form no more 
wood : all the carbonic acid which the plants now ab- 
sorb is employed for the production of nutritive matter 
for the following year : instead of woody fibre, starch is 
formed, and is difllised through every part of the plant 
by the autumnal sap (seve d'Aoiit)*. According to the 
observations of M. Heyer, the starch thus deposited in 
the body of the tree can be recognised in its known form 
by the aid of a good microscope. The barks of several 
aspens and pine trees f contain so much of this substance 

* Hartig, in Erdmann and Schweigger-Seidels JoMr77a/, V. 217, 1835. 

t It is well known that bread is made from the barks of pines in 
Sweden duiing famines. 

The following directions are given by Professor Aulenrielh for 
preparing a palatable and nutritious bread from the beech and other 
woods destitute of turpentine. Every thing soluble in water is first 
removed by frequent maceration and boiling, the wood is then to be 
reduced to a minute state of division, not merely into fine fibres, but 
actual powder ; and after being repeatedly subjected to heat in an 
oven, is ground in the usual manner of corn. Wood thus prepared, 



176 THE ART OF CULTURE. 

that it can be extracted from them as from potatoes, by 
trituration with water. It exists also in the roots and 
other parts of perennial plants. A very early winter or 
sudden change of temperature prevents the formation of 
this provision for the following year ; the wood, as in 
the case of the vine-stock, for example, does not ripen, 
and its growth is in the next year very limited. 

From the starch thus accumulated, sugar and gum 
are produced in the succeeding spring, while from the 
gum those constituents of the leaves and young sprouts 
which contain no nitrogen, are in their turn formed. 
After potatoes have germinated, the quantity of starch 
in them is found diminished. The juice of the maple- 
tree ceases to be sweet from the loss of sugar when its 
buds, blossoms, and leaves attain their maturity. 

The branch of a willow, which contains a large quan- 
tity of granules of starch in every part of its woody sub- 
stance, puts forth both roots and leaves in pure distilled 
rain-water ; but in proportion as it grows, the starch 
disappears, it being evidently exhausted for the forma- 
tion of the roots and leaves. In the course of these 
experiments, J\I. Heyer made the interesting observa- 
tion, that such branches when placed in snow-water 
(which contains ammonia) produced roots three or four 
times longer than those which they formed in pure dis- 
according to the author, acquires the smell and taste of corn flour. 
It is, however, never quite white. It agrees with corn flour in not 
fermenting without the addition of leaven, and in this case some 
leaven of corn flour is found to answer best. With this it makes a 
perfectly uniform and spongy bread ; and when it is thoroughly 
baked, and has much crust, it has a much better taste of bread than 
what in time of scarcity is prepared from the bran and husks of corn. 
Wood-flour also, boiled in water, forms a thick, tough, trembling 
jelly, which is very nutritious. — Philosophical Transactions, 1827, 



NUTRITION AND GROWTH OF PLANTS. 177 

tilled water, and that this pure water remained clear, 
while the rain-water gradually acquired a yellow color. 

Upon the blossoming of the sugar-cane, likewise, 
part of the sugar disappears : and it has been ascertain- 
ed, that the sugar does not accumulate in the beet-root 
until after the leaves are completely formed. 

Much attention has recently been drawn to the fact 
that the produce of potatoes may be much increased by- 
plucking off the blossoms from the plants producing 
them, a result quite consistent with theory. This im- 
portant observation has been completely confirmed by 
M. Zeller, the director of the Agricultural Society at 
Darmstadt. In the year 1839 two fields of the same 
size, lying side by side and manured in the same man- 
ner, were planted with potatoes. When the plants had 
flowered, the blossoms were removed from those in one 
field, while those in the other field were left untouched. 
The former produced 47 bolls, the latter only 37 bolls. 

These well-authenticated observations remove every 
doubt as to the part which sugar, starch, and gum play 
in the development of plants ; and it ceases to be enig- 
matical, why these three substances exercise no influ- 
ence on the growth or process of nutrition of a matured 
plant, when supplied to them as food. 

The accumulation of starch in plants during the au- 
tumn has been compared, although certainly errone- 
ously, to the fattening of hibernating animals before 
their winter sleep ; but in these animals every vital 
function except the process of respiration is suspended, 
and they only require, like a lamp slowly burning, a 
substance rich in carbon and hydrogen to support the 
process of combustion in the lungs. On their awaken- 
ing from their torpor in the spring, the fat has disap- 



178 THE ART OF CULTURE. 

peared, but has not served as nourishment. It has not 
caused the least increase in any part of their body, 
neither has it changed the quahty of any of their organs. 
With nutrition, properly so called, the fat in these ani- 
mals has not the least connexion. 

The annual plants form and collect their future nour- 
ishment in the same way as the perennial ; they store 
it in their seeds in the form of vegetable albumen, 
starch, and gum, which are used by the germs for the 
formation of their leaves and first radical fibres. The 
proper nutrition of the plants, their increase in size, 
begins after these organs are formed. 

Every germ and every bud of a perennial plant is 
the engrafted embryo of a new individual, while the 
nutriment accumulated in the stem and roots, corre- 
sponds to the albumen of the seeds. 

Nutritive matters are, correctly speaking, those sub- 
stances which, when presented from without, are capa- 
ble of sustaining the life and all the functions of an 
organism, by furnishing to the different parts of plants 
the materials for the production of their peculiar con- 
stituents. 

In animals, the blood is the source of the material of 
the muscles and nerves ; by one of its component parts, 
the blood supports the process of respiration, by others, 
the peculiar vital functions ; every part of the body is 
supplied with nourishment by it, but its own production 
is a special function, without which we could not con- 
ceive life to continue. If we destroy the activity of the 
organs which produce it, or if we inject the blood of one 
animal into the veins of another, at all events, if we 
carry this beyond certain limits, death is the conse- 
quence. 



NUTRITION AND GROWTH OF PLANTS. 179 

If we could introduce into a tree woody fibre in state 
of solution, it would be the sanfie thing as placing a po- 
tato-plant to vegetate in a paste of starch. The office 
of the leaves is to form starch, woody fibre, and sugar ; 
consequently, if we convey these substances through 
the roots, the vital functions of the leaves must cease, 
and if the process of assimilation cannot take another 
form, the plant must die. 

Other substances must be present in a plant, besides 
the starch, sugar, and gum, if these are to take part in 
the development of the germ, leaves, and first radicle 
fibres. There is no doubt that a grain of wheat con- 
tains within itself the component parts of the germ and 
of the radicle fibres, and we must suppose, exactly in 
the proportion necessary for their formation. These 
component parts are starch and gluten ; and it is evident 
that neither of them alone, but that both simultaneously 
assist in the formation of the root, for they both suffer 
changes under the action of air, moisture, and a suitable 
temperature. The starch is converted into sugar, and 
the gluten also assumes a new form, and both acquire 
the capability of being dissolved in water, and of thus 
being conveyed to every part of the plant. Both the 
starch and the gum are completely consumed in the 
formation of the first part of the roots and leaves ; an 
excess of either could not be used in the formation of 
leaves, or in any other way. 

The conversion of starch into sugar during the ger- 
mination of grain is ascribed to a vegetable principle 
called diastase, which is generated during the act of 
commencing germination. But this mode of transfor- 
mation can also be effected by gluten, although it re- 
quires a longer time. Seeds which have germinated, 



180 THE ART OF CULTURE. 

always contain much more diastase than is necessary for 
the conversion of their starch into sugar, for five parts 
by weight of starch can be converted into sugar by one 
part of raahed barley. This excess of diastase can by 
no means be regarded as accidental, for, like the starch, 
it aids in the formation of the first organs of the young 
plant, and disappears with the sugar ; diastase contains 
nitrogen and furnishes the elements of vegetable albu- 
men. 

Carbonic acid, water, and ammonia are the food of 
fully-developed plants ; starch, sugar, and gum serve, 
when accompanied by an azotized substance, to sustain 
the embryo, until its first organs of nutrition are unfold- 
ed. The nutrition of a foetus and development of an 
egg proceed in a totally different manner from that of 
an animal which is separated from its parent ; the ex- 
clusion of air does not endanger the life of the foetus, 
but would certainly cause the death of the independent 
animal. In the same manner, pure water is more ad- 
vantageous to the growth of a young plant, than that 
containing carbonic acid, but after a month the reverse 
is the case. 

The formation of sugar in maple-trees does not take 
place in the roots, but in the woody substance of the 
stem. The quantity of sugar in the sap augments until 
it reaches a certain height in the stem of the plant, 
above which point it remains stationary. 

Just as germinating barley produces a substance 
which, in contact with starch, causes it to lose its in- 
solubility and to become sugar, so in the roots of the 
maple, at the commencement of vegetation, a substance 
must be formed, which, being dissolved in water, per- 
meates the wood of the trunk, and converts into sugar 



NUTRITION AND GROWTH OF PLANTS. 181 

the Starch, or whatever it may be, which it finds depos- 
ited there. It is certain, that when a hole is bored into 
the trunk of a maple-tree just above its roots, filled with 
sugar, and then closed again, the sugar is dissolved by 
the ascending sap. It is further possible, that this 
sugar may be disposed of in the same manner as that 
formed in the trunks ; at all events it is certam, that the 
introduction of it does not prevent the action of the juice 
upon the starch, and since the quantity of sugar pres- 
ent is now greater than can be exhausted by the leaves 
and buds, it is excreted from the surface of the leaves 
or bark. Certain diseases of trees, for example, that 
called honey-dew, evidently depend on the want of the 
^ue proportion between the quantity of the azotized and 
that of unazotized substances which are supplied to them 
as nutriment. 

I^ whatever form, therefore, we supply plants with 
those substances which are the products of their own ac- 
tion, in no instance do they appear to have any efi^ect 
.^ upon their growth, or to replace what they have lost. 
Sugar, gum, and starch are not food for plants, and the 
same must be said of humic acid, which is so closely 
allied to them in composition. 

If now we direct our attention to the particular organs 
of a plant, we find every fibre and every particle of 
wood surrounded by a juice containing an azotized mat- 
ter : while the starch granules and sugar are enclosed in 
cells formed of a substance containing nitrogen. Indeed 
everywhere, in all the juices of the fruits and blossoms, 
we find a substance, destitute of nitrogen, accompanied 
by one which contains that element. 

The wood of the stem cannot be formed, quasi wood, 
in the leaves, but another substance must be produced, 
16 



182 THE ART OF CULTURE. 

which is capable of being transformed into wood. This 
substance must be in a stale of solution, and accompa- 
nied by a compound containing nitrogen ; it is very 
probable, that the wood and the vegetable gluten, the 
starch granules and the cells containing them, are formed 
simultaneously, and in this case, a certain fixed propor- 
tion between them would be a condition necessary for 
their production. 

According to this view, the assimilation of the sub- 
stances generated in the leaves will (cfcteris paribus) 
depend on the quantity of nitrogen contained in the 
food. • When a sufficient quantity of nitrogen is not- 
present to aid in the assimilation of the substances which 
do not contain it, these substances will be separated as» 
excrements from the bark, roots, leaves, and branches. 
The exudations of mannite, gum, and sugar, in strong 
and healthy plants, cannot be ascribed to any ^her 
cause.* 

Analogous phenomena are presented by the process 
of digestion in the human organism. In order that the 
loss which every part of the body sustains by the pro- 
cesses of respiration and perspiration may be restored to 
it, the organs of digestion require to be supplied with 
food, consisting of substances containing nitrogen, and of 
others destitute of it, in definite proportions. If the 
substances which do not contain nitrogen preponderate, 
either they will be expended in the formation of fat, or 



* M. Trapp, in Giessen, possesses a Clerodendron fragrans, which 
grows in the house, and exudes on the surface of its leaves in Sep- 
tember large colorless drops of sugar-candy, which form regular crys- 
tals upon drying; I am not aware whether the juice of this plant con- 
tains sugar. — L. 



INFLUENCE OF THE FOOD ON THE PRODUCE. 183 

they will pass unchanged through the organism. This 
is particularly observed in those people who live almost 
exclusively upon potatoes ; their excrements contain a 
large quantity of unchanged granules of starch, of which 
no trace can be detected when gluten, or flesh, is taken 
in proper proportions, because, in this case, the starch 
has been rendered capable of assimilation. Potatoes 
which, when mixed with hay alone, are scarcely capa- 
ble of supporting the strength of a horse, form with 
bread and oats a strong and wholesome fodder. 

It will be evident from the preceding considerations, 
that the products generated by a plant may vary exceed- 
ingly, according to the substances given it as food. A 
superabundance of carbon in the state of carbonic acid 
conveyed through the roots of plants, without being ac- 
companied by nitrogen, cannot be converted either into 
gluten, albumen, wood, 04* any other component part of an 
.organ ; but either it will be separated in the form of ex- 
crements, such as sugar, starch, oil, wax, resin, man- 
nite, or gum, or these substances will be deposited in 
greater or less quantity in the wide cells and vessels. 

The quantity of gluten, vegetable albumen, and mu- 
cilage, will augment when plants are supplied with an 
excess of food containing nitrogen ; and ammoniacal 
salts will remain in the sap, when, for example, in the 
culture of the beet, we manure the soil with a highly ni- 
trogenous substance, or when we suppress the functions 
of the leaves, by removing them from the plant. 

We know that the ananas (pine apple) is scarcely 
eatable in its wild state, and that it shoots forth a great 
quantity of leaves, when treated with rich animal ma- 
nure, without the fruit on that account acquiring a large 
amount of sugar ; that the quantity of starch in potatoes 



184 THE ART OF CULTURE. 

increases, when the soil contains much humus, but de- 
creases when the soil is manured with strong animal ma- 
nure, although then the number of cells increases, the 
potatoes acquiring in the first case a mealy, and in the 
second, a soapy, consistence. Beet roots taken from a 
barren sandy soil contain a maximum of sugar, and no 
ammoniacal salts ; and the Teltowa turnip loses its 
mealy state in a manured land, because there, all the 
circumstances necessary for the formation of cells are 
united. 

An abnormal production of certain component parts 
of plants presupposes a power and capability of assimi- 
lation, to which the most powerful chemical action can- 
not be compared. The best idea of it may be formed, 
by considering that it surpasses in power the strongest 
galvanic battery, with which we are not able to separate 
the oxygen from carbonic acid. The affinity of chlorine 
for hydrogen, and its power to decompose water under 
the influence of liglu, and set at liberty its oxygen, 
cannot be considered as at all equalling the power and 
energy with which a leaf separated from a plant decom- 
poses the carbonic acid which it absorbs. 

The common opinion that only the direct solar rays 
can effect the decomposition of carbonic acid in the 
leaves of plants, and that reflected or diff"used light does 
not possess this property, is wholly an error, for 'exactly 
the same constituents are generated in a number of 
plants, whether the direct rays of the sun fall upon them, 
or whether they grow in the shade. They require light, 
and, indeed, sun light, but it is not necessary that the 
direct rays of the sun reach them. Their functions cer- 
tainly proceed with greater intensity and rapidity in sun- 
shine, than in the diffused light of day ; but there is 



INFLUENCE OF LIGHT. 185 

nothing more in this than the similar action which light 
exercises on ordinary chemical combinations, it merely 
accelerates in a greater or less degree the action already 
subsisting. 

Chlorine and hydrogen combining form muriatic acid. 
This combination is effected in a few hours in common 
daylight, but it ensues instantly with a violent explosion, 
under exposure to the direct solar rays, whilst not the 
slightest change in the two gases takes place in perfect 
darkness. When the liquid hydrocarburet of chlorine, 
resulting from the union of the olefiant gas of the Dutch 
chemists with chlorine, is exposed in a vessel with chlo- 
rine gas to the direct solar rays, chloride of carbon is 
immediately produced ; but the same compound can be 
obtained with equal facility in the diffused light of day, 
a longer time only being required. When this experi- 
ment is performed in the way first mentioned, two pro- 
ducts only are observed (muriatic acid and perchloride 
of carbon) ; whilst by the latter method, a class of in- 
termediate bodies are produced, in which the quantity of 
chlorine constantly augments, until at last the whole li- 
quid hydrocarburet of chlorine is converted into the 
same two products as in the first case. Here, also, not 
the slightest trace of decomposition takes place in the 
dark. Nitric acid is decomposed in common daylight 
into oxygen, and peroxide of nitrogen and chloride of 
silver becomes black in the diffused llghi of day, as well 
as in the direct solar rays ; — in short, all actions of a 
similar kind proceed in the same way in diffused light as 
well as in the solar light, the only difference consisting 
in the time in which they are effected. It cannot be 
otherwise in plants, for the mode of their nutriment is 
the same in all, and their component substances afford 
16* 



186 THE ART OF CULTURE. 

proof, that their food has suffered absolutely the same 
change, whether they grow in the sunshine or in the 
shade. 

All the carbonic acid, therefore, which we supply to 
a plant will undergo a transformation, provided its quan- 
tity be not greater than can be decomposed by the 
leaves. We know that an excess of carbonic acid kills 
plants, but we know also that nitrogen, to a certain 
degree, is not essential for the decomposition of car- 
bonic acid. All the experiments hitherto instituted, 
prove that fresh leaves placed in water, impregnated 
with carbonic acid, and exposed to the influence of solar 
light, emit oxygen gas, whilst the carbonic acid disap- 
pears. Now, in these experiments, no nitrogen is sup- 
plied at the same time with the carbonic acid ; hence no 
other conclusion can be drawn from them, than that ni- 
trogen is not necessary for the decomposition of carbonic 
acid, — for the exercise, therefore, of one of the func- 
tions of plants. And yet the presence of a substance 
containing this element appears to be indispensable for 
the assimilation of the products newly formed by the 
decomposition of the carbonic acid, and their consequent 
adaptation for entering into the composition of the dif- 
ferent organs. 

. The carbon abstracted from the carbonic acid acquires 
in the leaves a new form, in which it is soluble and 
transferable to all parts of the phnt. In this new form 
the carbon aids in constituting several new products ; 
these are named sugar when they possess a sweet taste, 
gum or mucilage when tasteless, and excrementitions 
matters when expelled by the roots. 

Hence it is evident, that the quantity and quality of 
the substances generated by the vital processes of a plant 



INFLUENCE OF THE FOOD ON THE PRODUCE. 187 

will vary according to the proportion of the different 
kinds of food with which it is supplied. The develop- 
ment of every part of a plant in a free and uncultivated 
state depends on the amount and nature of the food 
afforded to it, by the spot on which it grows. A plant 
is developed on the most sterile and unfruitful soil, as 
well as on the most luxuriant and fertile, the only differ- 
ence which can be observed being in its height and size, 
in the number of its twigs, branches, leaves, blossoms, 
and fruit. Whilst the individual organs of a plant in- 
crease on a fertile soil, they diminish on another, where 
those substances which are necessary for their formation 
are not so bountifully supplied ; and the proportion of 
the constituents, which contain nitrogen, and of those 
which do not, in plants varies with the amount of nitro- 
geneous matters in their food. 

The development of the stem, leaves, blossoms, and 
fruit of plants is dependent on certain conditions, the 
knowledge of which enables us to exercise some influ- 
ence on their internal constituents as well as on their 
size. It is the duty of the natural philosopher to dis- 
cover what these conditions are ; for the fundamental 
principles of agriculture must be based on a knowledge 
of them. There is no profession which can be com- 
pared in importance with that of agriculture, for to it 
belongs the production of food for man and animals ; 
on it depends the welfare and development of the whole 
human species, the riches of states, and all commerce. 
There is no other profession in which the application of 
correct principle is productive of more beneficial effects, 
or is of greater and more decided influence. Hence it 
appears quite unaccountable, that we may vainly search 



188 THE ART OF CULTURE. 

for one leading principle in the writings of agriculturists 
and vegetable physiologists. 

The methods employed in the cultivation of land are 
different in every country, and in every district ; and 
when we inquire the causes of these differences we re- 
ceive the answer, that they depend upon circumstances. 
(Les circonstances font les assolemens.) No answer 
could show ignorance more plainly, since no one has 
ever yet devoted himself to ascertain what these circum- 
stances are. Thus also when we inquire in what manner 
manine acts, we are answered by the most intelligent 
men, that its action is covered by the veil of Isis ; and 
when we demand further what this means, we discover 
merely that the excrements of men and animals are sup- 
posed to contain an incomprehensible something which 
assists in the nutrition of plants, and increases tlieir size, 
this opinion is embraced without even an atten)pt being 
made to discover the component parts of manure, or to 
become acquainted with its nature. 

In addition to the general conditions, such as heat, 
light, moisture, and the component parts of the atmo- 
sphere, which are necessary for the growth of all plants, 
certain substances are found to exercise a peculiar in- 
fluence on the development of particular faniilies. These 
substances either are already contained in the soil, or are 
supplied to it in the form of the matters known under 
the general name of manure. But what does the soil 
contain, and what are the components of the substances 
used as manure .'' Until these points are satisfactorily 
determined, a rational system of agriculture cannot exist. 
The power and knowledge of the [)hysiologist, of the 
agriculturist and chemist must be united for the com- 



OBJECT OF AGRICULTURE. 189 

plete solution of these questions ; and in order to attain 
this end, a commencement must be made. 

The general object of agricuhure is to produce in the 
most advantageous manner certain quahties, or a maxi- 
mum size, in certain parts or organs of particular plants. 
Now, this object can be attained only by the application 
of those substances which we know to be indispensable 
to the development of these parts or organs, or by sup- 
plying the conditions necessary to the production of the 
qualities desired. 

The rules of a rational system of agriculture should 
enable us, therefore, to give to each plant that which it 
requires for the attainment of the object in view. 

The special object of agriculture is to obtain an 
abnormal development and production of certain parts 
of plants, or of certain vegetable matters, which are 
employed as food for man and animals, or for the pur- 
poses of industry. 

The means employed for effecting these two purposes 
are very different. Thus the mode of culture, employed 
for the purpose of procuring fine pliable straw for Flo- 
rentine hats, is the very opposite to that which must be 
adopted in order to produce a maximum of corn from 
the same plant. Peculiar methods must be used for the 
production of nitrogen in the seeds, others for giving 
strength and solidity to the straw, and others again must 
be followed when we wish to give such strength and 
solidity to the straw as will enable it to bear the weight 
of the ears. 

We must proceed in the culture of plants in precisely 
the same manner as we do in the fattening of animals. 
The flesh of the slag and roe, or of wild animals in 
general, is quite devoid of fat, like the muscular flesh 



190 THE ART OF CULTURE. 

of the Arab ; or it contains only small quantities of it. 
The production of flesh and fat may be artificially in- 
creased ; all domestic animals, for example, contain much 
fat. We give food to animals, which increases the 
activity of certain organs, and is itself capable of being 
transformed into fat. We add to the quantity of food, 
or we lessen the processes of respiration and perspira- 
tion by preventing motion. The conditions necessary 
to effect this purpose in birds are different from those in 
quadrupeds ; and it is well known that charcoal powder 
produces such an excessive growth of the liver of a 
goose, as at length causes the death of the animal. 

The increase or diminution of the vital activity of 
vegetables depends only on heat and solar light, which 
we have not arbitrarily at our disposal : all that we can 
do is to supply those substances which are adapted for 
assimilation by the power already present in the organs 
of the plant. But what then are these substances .'' They 
may easily be detected by the examination of a soil, 
which is always fertile in given cosmical and atmospheric 
conditions ; for it is evident, that the knowledge of its 
state and composition must enable us to discover the 
circumstances under which a sterile soil may be rendered 
fertile. It is the duty of the chemist to explain the 
composition of a fertile soil, but the discovery of its 
proper state or condition belongs to the agriculturist ; 
our present business lies only with the former. 

Arable land is originally formed by the crumbling of 
rocks, and its properties depend on the nature of their 
principal component parts. Sand, clay, and lime, are 
the names given to the principal constituents of the dif- 
ferent kinds of soil. 

Pure sand and pure limestone, in which there are no 



COMPOSITION OF SOILS. 191 

Other inorganic substances except siliceous earth, car- 
bonate or silicate of lime, form absolutely barren soils. 
But argillaceous earths form always a part of fertile soils. 
Now from whence come the argillaceous earths in arable 
land ; what are their constituents, and what part do they 
play in favoring vegetation ? They are produced by 
the disintegration of aluminous minerals by the action of 
the weather ; the common potash and soda felspars, 
Labrador spar, mica, and the zeolites, are the most 
common aluminous earths, which undergo this change. 
These minerals are found mixed with other substances 
in granite, gneiss, mica-slate, porphyry, clay-slate, grau- 
wacke, and the volcanic rocks, basalt, clinkstone, and 
lava. In the grauwacke, we have pure quartz, clay-slate, 
and lime ; in the sandstones, quartz and loam. The 
transition limestone and the dolomites contain an inter- 
mixture of clay, felspar, porphyry, and clay-slate ; and 
the mountain limestone is remarkable for the quantity of 
argillaceous earths which it contains. Jura limestone 
contains 3 — 20, that of the Wurtemberg Alps 45 — 50 
per cent, of these earths. And in the muschelkalk and 
the calcaire grassier they exist in greater or less quan- 
tity. 

It is known, that the aluminous minerals are the most 
widely diffused on the surface of the earth, and as we 
have already mentioned, all fertile soils, or soils capable 
of culture, contain alumina as an invariable constituent. 
There must, therefore, be something in aluminous earth 
which enables it to exercise an influence on the life of 
plants, and to assist in their development. The prop- 
erty on which this depends is that of its invariably con- 
taining potash and soda. 

Alumina exercises only an indirect influence on vege- 



192 THE ART OF CULTURE. 

talion, by its power of attraciing and retaining water 
and ammonia ; it is itself very rarely found in the ashes 
of plants, but silica is always present, having in most 
places entered the plants by means of alkalies. In or- 
der to form a distinct conception of the quantities of 
alkalies in aluminous minerals it must be remembered 
that felspar contains 17f per cent, of potash, albite 
11.43 per cent, of soda, and mica 3 — 5 per cent. ; 
and that zeolite contains 13 — 16 per cent, of both alka- 
lies taken together. The late analyses of Ch. Gmelin, 
Lowe, Fricke, Bleyer, and Redtenbache/r, have also 
shown, that ^basalt contains from f to 3 per cent, of 
potash, and from 5 — 7 per cent, of soda, that clay-slate 
contains from 2.75 — 3.31 per cent, of potash, and 
loam from 1^ — 4 per cent, of potash. 

If, now, we calculate from these data, and from the 
specific weights of the different substances, how much 
potash must be contained in a layer of soil, which has 
been formed by the disintegration of 40,000 square feet 
(1 Hessian acre) of one of these rocks to the depth of 
20 inches, we find that a soil of 

Felspar contains 1,152,000 lbs. 

Clink-stone " from 200,000 to 400,000 " 

Basalt " " 47,500 " 75,000 " 

Clay-slate " " 100,000 " 200,000 " 

Loam " " 87,000 " 300,000 " 

Potash is present in all clays ; according to Fuchs, it is 
contained even in marl ; it has been found in all the 
argillaceous earths in which it has been sought. The 
fact that they contain potash may be proved in the clays 
of the transition and stratified mountains, as well as in 
the recent formations surrounding Berlin, by simply di- 
gesting them with sulphuric acid, by which process 



OF THE FERTILITY OF SOILS. 193 

alum is formed. (Mltscherlich.) It is well known 
also, to all manufacturers of alum, that the leys contain 
a certain quantity of this salt ready formed, the potash 
of which has its origin from the ashes of the stone and 
brown coal, which contain much argillaceous earth. 

When we consider ihis extraordinary distribution of 
potash over the surface of the earth, is it reasonable to 
have recourse to the idea, that the presence of this alkali 
in plants is due to the generation of a metallic oxide by 
a peculiar organic process from the component parts of 
the atmosphere. This opinion found adherents even 
after the method of detecting potash in soils was known, 
and suppositions of the same kind may be found even in 
the writings of some physiologists of the present day. 
Such opinions belong properly to the time when flint 
was conceived to be a product of chalk, and when every 
thing, which appeared incomprehensible on account of 
not having been investigated, was explained by assump- 
tions far more incomprehensible. 

A thousandth part of loam mixed with the quartz in 
new red sandstone, or with the lime in the difTerent 
limestone formations, affords as much potash to a soil 
only 20 inches in depth as is sufficient to supply a forest 
of pines growing upon it for a century. A single cubic 
foot of felspar is sufficient to supply a wood, covering a 
surface of 40,000 square feet, with the potash required 
for five years. 

Land of the greatest fertility contains argillaceous- 
earths and other disintegrated nainerals with chalk and 
sand, in such a proportion as to give fiee access to air 
and moisture. The land in the vicinity of Vesuvius 
may be considered as the type of a fertile soil, and its 
17 



194 THE ART OF CULTURE. 

fertility is greater or less in different parts, according to 
the proportion of clay or sand which it contains. 

The soil which is formed by the disintegration of lava 
cannot possibly, on account of its origin, contain the 
smallest trace of vegetable matter, and yet it is well 
known, that when the volcanic ashes have been exposed 
for some time to the influence of air and moisture, a soil 
is gradually formed in which all kinds of plants grow 
with the greatest luxuriance. This fertility is owing to 
the alkalies which are contained in the lava, and which, 
by exposure to the weather, are rendered capable of 
being absorbed by plants. Thousands of years have 
been necessary to convert stones and rocks into the soil 
of arable land, and thousands of years more will be 
requisite for their perfect reduction, that is, for the com- 
plete exhaustion of their alkalies. 

We see from the composition of the water in rivers, 
streamlets, and springs, how little rain-water is able to 
extract alkali from a soil, even after a term of years ; 
this water is generally soft, and the common salt, which 
even the softest invariably contains, proves that those 
alkaline salts, which are carried to the sea by rivers and 
streams, are returned again to the land by wind and rain. 

Nature itself shows us what plants require at the com- 
mencement of the development of their germs and first 
radical fibres. Becquercl has shown that the graminea, 
iFguminosft, cracifcrcE, cichoracccB, umhelUfera^ conifercB, 
and cucurbitacete emit acetic acid during germination. 
A plant which has just broken through the soil, and a 
leaf just burst open from the bud, furnish ashes by in- 
cineration, which contain as much, and generally more, 
of alkaline salts than at any period of their life. (De 
Saussure). Now we know also from the experiments 



OF THE FERTILITY OF SOILS. 195 

of Becquerel in what manner these alkaline salts enter 
young plants ; the acetic acid formed during germina- 
tion is diffused through the wet or moist soil, becomes 
saturated with lime, magnesia, and alkalies, and is again 
absorbed by the radicle fibres in the form of neutral 
salts. After the cessation of life, when plants are sub- 
jected to decomposition by means of decay and putre- 
faction, the soil receives again that which had been 
extracted from it. 

Let us suppose that a soil has been formed by the 
action of the weather on the component parts of granite, 
grauwacke, mountain limestone, or porphyry, and that 
nothing has vegetated for thousands of years. Now this 
soil would have become a magazine of alkalies, in a 
condition favorable for their assimilation by the roots of 
plants. 

The interesting experiments of Siruve have proved 
that water impregnated with carbonic acid decomposes 
rocks which contain alkalies, and then dissolves a part 
of the alkaline carbonates. It is evident that plants, 
also, by producing carbonic acid during their decay, 
and by means of the acids which exude from their roots 
in the living state, contribute no less powerfully to de- 
stroy the coherence of rocks. Next to the action of air, 
water, and change of temperature, plants themselves are 
the most powerful agents in effecting the disintegration 
of rocks. 

Air, water, and the change of temperature prepare 
the different species of rocks for yielding to plants the 
alkalies which they contain. A soil which has been 
exposed for centuries to all the influences which effect 
the disintegration of rocks, but from which the alkalies 
have not been removed, will be able to afford the means 



196 THE ART or CULTURE. 

of nourishment to those vegetables which require alka- 
lies for its growth during many years ; but it must grad- 
ually become exhausted, unless those alkalies which 
have been removed are again replaced ; a period, there- 
fore, will arrive, when it will be necessary to expose it, 
from time to time, to a further disintegration, in order 
to obtain a new supply of soluble alkalies. For small 
as is the quantity of alkali which plants require, it is 
nevertheless quite indispensable for their perfect devel- 
opment. But when one or more years have elapsed 
without any alkalies having been extracted from the 
soil, a new harvest may be expected. 

The first colonists of Virginia found a country, the 
soil of which was similar to that mentioned above ; har- 
vests of wheat and tobacco were obtained for a century 
from one and the same field without the aid of manure, 
but now whole districts are converted into unfruitful 
pasture land, which without manure produces neither 
wheat nor tobacco. From every acre of this land, 
there were removed in the space of one hundred years 
1,200 lbs. of alkalies in leaves, grain, and straw; it 
became unfruitful therefore, because it was deprived of 
every particle of alkali, which had been reduced to a 
soluble state, and because that which was rendered 
soluble again in the space of one year, was not sufficient 
to satisfy the demands of the plants. Almost all the 
cultivated land in Europe is in this condition ; fallow is 
the term applied to land left at rest for further disinte- 
gration. It is the greatest possible mistake to suppose 
that the temporary diminution of fertility in a soil is 
owing to the loss of humus ; it is the mere consequence 
of the exhaustion of the alkalies. 

Let us consider the condition of the country around 



OF THE FERTILITY OF SOILS. 197 

Naples, which is famed for its fruitful corn-land ; the 
farms and villages are situated from 18 to 24 miles dis- 
tant from one another, and between them there are no 
roads, and consequently no transportation of manure. 
Now corn has been cultivated on this land for thousands 
of years, without any part of that which is annually re- 
moved from the soil being artificially restored to it. 
How can any influence be ascribed to humus under 
such circumstances, when it is not even known whether 
humus was ever contained in the soil ? 

The method of culture in that district completely ex- 
plains the permanent fertility. It appears very bad in the 
eyes of our agriculturists, but there it is the best plan 
which could be adopted. A field is cultivated once 
every three years, and is in the intervals allowed to 
serve as a sparing pasture for cattle. The soil experi- 
ences no change in the two years during which it there 
lies fallow, further than that it is exposed to the influ- 
ence of the weather, by which a fresh portion of the 
alkalies contained in it are again set free or rendered 
soluble. The animals fed on these fields yield nothing 
to these soils which they did not formerly possess. 
The weeds upon which they live spring from the soil, 
and that which they return to it as excrement, must 
always be less than that which they extract. The field, 
therefore, can have gained nothing from the mere feed- 
ing of cattle upon them ; on the contrary, the soil must 
have lost some of its constituents. 

Experience has shown in agriculture, that wheat 
should not be cultivated after wheat on the same soil, 
for it belongs with tobacco to the plants which exhaust 
a soil. But if the humus of a soil gives it the power of 
producing corn, how happens it that wheat does not 
17* 



19S THE ART OF CULTURE. 

thrive in many parts of Brazil, where the soils are par- 
ticularly rich in this substance, or in our own climate, 
in soils formed of mouldered wood ; that its stalk under 
these circumstances attains no strength, and droops pre- 
maturely ? The cause is this, — that the strength of 
the stalk is due to silicate of potash, and that the corn 
requires phosphate of magnesia, neither of which sub- 
stances a soil of humus can afford, since it does not 
contain them ; the plant may indeed, under such cir- 
cumstances, become an herb, but will not bear fruit. 

Again, how does it happen that wheat does not flour- 
ish on a sandy soil, and that a calcareous soil is also 
unsuitable for its growth, unless it be mixed with a 
considerable quantity of clay ? It is because these soils 
do not contain alkalies in sufficient quantity, the growth 
of wheat being arrested by this circumstance, even 
should all other substances be presented in abundance. 

It is not mere accident that only trees of the fir tribe 
grow on the sandstone and limestone of the Carpathian 
mountains and the Jura, whilst we find on soils of 
gneiss, mica-slate, and granite in Bavaria, of clinkstone 
on the Rhone, of basalt in Vogelsberge, and of clay- 
slate on the Rhine and Eifel, the finest forests of other 
trees which cannot be produced on the sandy or calca- 
reous soils upon which pines thrive. It is explained by 
the fact, that trees, the leaves of which are renewed 
annually, require for their leaves six to ten times more 
alkalies than the fir-tree or pine, and hence, when they 
are placed in soils in which alkalies are contained in 
very small quantity, do not attain maturity.* When we 

* One thousand parts of tlie dry leaves of oaks yielded 55 parts of 
ashes, of which 24 parts consisted of alkalies soluble in water ; the 
same quantity of pine leaves gave only 21) parts of ashes, which con- 
tained 4 6 parts of soluble salts. (De Saussure.) 



or THE FERTILITY OF SOILS. 199 

see such trees growing on a sandy or calcareous soil, — 
the red-beech, the service-tree, and the wild-cherry, 
for example, thriving luxuriantly on limestone, we may 
be assured that alkalies are present in the soil, for they 
are necessary to their existence. Can we, then, regard 
it as remarkable, that such trees should thrive in Amer- 
ica, on those spots on which forests of pines which have 
grown and collected alkalies for centuries, have been 
burnt, and to which the alkalies are thus at once restor- 
ed ; or that the Spartium scoparium, Erysimum latifo- 
lium, Blitum copitaium, Senecio viscosus^ plants re- 
markable for the quantity of alkalies contained in their 
ashes, should grow with the greatest luxuriance on the 
localities of conflagrations.* 

Wheat will not grow on a soil which has produced 
wormwood, and, vice versa, wormwood does not thrive 
where wheat has grown, because they are mutually 
prejudicial by appropriating the alkalies of the soil. 

One hundred parts of the ^alks of wheal yield 15.5 
parts of ashes (H. Davy) ; the same quantity of the 
dry stalks of barley, 8. 54 parts (^Schrader) ; and one 
hundred parts of the stalks of oats, only 4.42 ; — the 
ashes of all these are of the same composition. 

We have in these facts a clear proof of what plants 
require for their growth. Upon the same field, which 
will yield only one harvest of wheat, two crops of bar- 
ley and three of oats may be raised. 

* After the great fire in London, large quantities of the Erysimum 
latifolium were observed growing on the spots where a fire had taken 
place. On a similar occasion, the Blitum capitalum was seen at 
Copenhagen, the Senecio viscosus in Nassau, and the Spartium sco- 
•parium in Languedoc. After the burnings of forests of pines in 
North America poplars grew on the same soil. {Franklin) 



200 THE ART OF CULTURE. 

AH plants of the grass kind require silicate of potash. 
Now this is conveyed to the soil, or rendered soluble in 
it by the irrigation of meadows. The equisetacecBj the 
reeds and species of cane, for example, which contain 
such large quantities of siliceous earth, or silicate of pot- 
ash, thrive luxuriantly in marshes, in argillaceous soils, 
and in ditches, streamlets, and other places, where the 
change of water renews constantly the supply of dis- 
solved sihca. The amount of silicate of potash removed 
from a meadow, in the form of hay, is very considerable. 
We need only call to mind the melted vitreous mass 
found on a meadow between INfanheim and Heidelberg 
after a thunder-storm. This mass was at first supposed 
to be a meteor, but was found on examination (by 
Gmeliii) to consist of silicate of potash ; a flash of 
lightning had struck a stack of hay, and nothing was found 
in its place except the melted ashes of the hay. 

Potash is not the only substance necessary for the ex- 
istence of most plants, indeed it has been already shown 
that the potash may be replaced, in many cases, by soda, 
magnesia, or lime ; but other substances, besides alkalies, 
are required to sustain the life of plants. 

Phosphoric acid has been found in the ashes of all 
plants hitherto examined, and always in combination with 
alkalies or alkaline earths. Most seeds contain certain 
quantities of phosphates. In the seeds of different kinds 
of corn, particularly, there is abundance of phosphate of 
magnesia. 

Plants obtain their phosphoric acid from the soil. It 
is a constituent of all land capable of cultivation, and 
even the heath at Liineburg contains it in appreciable 
quantity. Phosphoric acid has been detected, also, in 
all mineral waters in which its presence has been tested ; 



OF THE FERTILITY OF SOILS, 201 

and in those in which it has not been found, it has not 
been sought for. The most superficial strata of the de- 
posits of sulphuret of lead (galena) contain crystallized 
phosphate of lead (greenlead ore) ; clay-slate, which 
forms extensive strata, is covered in many places with 
crystals of phosphate of alumina ( ff^avellite) ; all its 
fractured surfaces are overlaid with it. Phosphate of 
lime (Apatite) is found even in the volcanic bowlders on 
the Laacher See in the Eifel, near Andernach. 

The soil in which plants grow furnishes them with 
phosphoric acid, and they in turn yield it to animals, to 
be used in the formation of their bones, and of those 
constituents of the brain which contain phosphorus. 
Much more phosphorus is thus afforded to the body than 
it requires, when flesh, bread, fruit, and husks of grain 
are used for food, and this excess in them is eliminated 
in the urine and the solid excrements. We may form 
an idea of the quantity of phosphate of magnesia con- 
tained in grain, when we consider that the concretions 
in the coecum of horses consist of phosphate of mag- 
nesia and ammonia, which must have been obtained 
from the hay and oats consumed as food. Twenty- 
nine of these stones were taken after death from the 
rectum of a horse belonging to a miller in Eberstadt, the 
total weight of which amounted to 31bs. ; and Dr. F. 
Simon has lately described a similar concretion found in 
the horse of a carrier, which weighed Iglb. 

It is evident that the seeds of corn could not be form- 
ed without phosphate of magnesia, whicU is one of their 
invariable constituents ; the plant could not under such 
circumstances, reach maturity. 

Some plants, however, extract other matters from the 
soil besides silica, potash, and phosphoric acid, which 



202 THE ART OF CULTURE. 

are essential constituents of the plants ordinarily culti- 
vated. These other matters, we must suppose, supply, 
in part at least, the place and perform the function of 
the substances just named. We may thus regard com- 
mon salt, sulphate of potash, nitre, chloride of potassi- 
um, and olher matters, as necessary constituents of 
several plants. 

Clay-slate contains generally small quantities of oxide 
of copper ; and soils formed from micaceous schist con- 
tain some metallic fluorides. Now, small quantities of 
these substances also are absorbed into plants, although 
we cannot affiim that they are necessary lo them. 

It appears that, in certain cases, fluoride of calcium* 
may take the place of the phosphate of lime in the bones 
and teeth ; f at least, it is impossible otherwise to explain 

* Fluorine is the base of the acid contained in Fluor or Derbyshire 
spar ; with hydrogen it forms the hydrofluoric acid. The acid is sepa- 
rated by heating fluor spar with sulphuric acid, and is distinguished 
by its power of corroding glass, and of uniting with its silica. Com- 
pounds of Fluorine are called Fluorides, of the acid Hijdrofluates. 
Calcium is the base of lime. 

! The earthy parts of bones are composed principally of the phos- 
phate and carbonate of lime in various proportions, variable in differ- 
ent animals, and mixed with small quantities, equally variable, of 
phosphate of magnesia and fluate of lime. By acting upon calcined 
bones with sulphuric acid fluoric acid is disengaged. The following 
analyses of the bones of man and horned cattle, are given by Ber- 

zelius. 

Human bone. Ox bone. 

Cartilage soluble in water, . . . 32.17 ) 03 on 

Vessels, ....... 1.13 J 

Subphosphate, and a little fluate of lime, . 53.04 57.35 

Carbonate of lime, 11.30 3.85 

Phosphate of magnesia, . . . . 1.16 2 05 

Soda and very little muriate of soda, . . 1 20 3.45 

10000 100.00 

The bones of man contain three times as much carbonate of lime 



FALLOW-CROPS. 203 

its constant presence in the bones of antediluvian animals, 
by which they are distinguished from those of a later 
period. The bones of human skulls found at Pompeii 
contain as much fluoric acid as those of animals of a for- 
mer world, for if they be placed in a state of powder in 
glass vessels, and digested with sulphuric acid, the interior 
of the vessel will, after twenty-four hours, be found 
powerfully corroded (Liebig) ; whilst the bones and 
teeth of animals of the present day contain only traces 
of it (^Berzelius) . 

Dt Saussure remarked, that plants require unequal 
quantities of the component parts of soils in different 
stages of their development ; an observation of much 
importance in considering the growth of plants. Thus, 
wheat yielded xl^-o of ashes a month before blossoming, 
yllg while in blossom, and y§|o after the ripening of 
the seeds. It is therefore evident, that wheat from the 

as those of the ox, and the latter are richer in phosphate of lime and 
magnesia in the same proportion. 

The following are the relative proportions of phosphate and car- 
bonate of lime in bones of different animals, according lo De Barros. 
Phosphate of Lime. Carbonate of Lime. 
Lion, .... 95.0 2.5 

Sheep, .... 80.0 19,3 

Hen, .... 88.9 10.4 

Frog 95.2 2.4 

Fish, .... 91.9 5.3 

The enamel of the teeth is composed of 





Human. 


Ox. 


Phosphate of lime, 


. 88.5 


85.0 


Carbonate of " . . 


8.0 


7.1 


Phosphate of magnesia. 


. 1.5 


3.0 


Soda, .... 


0.0 


1.4 


Membrane, alkali and water, 


. 2.0 


3.5 



100.0 100.0 



204 THE ART OF CULTURE. 

time of its flowering restores a part of its organic con- 
stituents to the soil, althougli the phosphate of magnesia 
remains in the seeds. 

The fallow-time, as we have already shown, is that 
period of culture, during which land is exposed to a pro- 
gressive disintegration by means of the influence of the 
atmosphere, for the purpose of rendering a certain quan- 
tity of alkalies capable of being appropriated by plants. 

Now, it is evident, that the careful tilling of fallow 
land must increase and accelerate this disintegration. 
For the purpose of agriculture, it is quite indifferent, 
whether the land is covered with weeds, or with a plant 
which does not abstract the potash enclosed in it. Now 
many plants in the family of the leguminosce^ are remarka- 
ble on account of the small quantity of alkalies or salts 
in general, which they contain ; the Vicia faba (Wind- 
sor bean), for example, contains no free alkalies, and not 
one per cent, of the phosphates of lime and magnesia. 
(Einhof.) The bean of the Phaseolus Vulgaris (Kid- 
ney bean) contains only traces of salts. [Braconnot.) 
The stem of the Medicago saliva (Lucerne) contains 
only 0.83 per cent., that of the Ervum lens (Lentil) 
only 0.57 of phosphate of lime with albumen. [Crome.) 
Buck-wheat dried in the sun yields only 0.681 per cent. 
of ashes, of which 0.09 parts are soluble salts. {Zennech) .* 
These plants belong to those which are termed fallow- 
crops, and the cause wherefore they do not exercise any 

* The small quantity of phosphates which the seeds of the lentils, 
beans and peas contain, must be the cause of their small value as 
articles of nourishment, since they surpass all other vegetable food in 
the quantity of nitrogen which enters into their composition. But 
as the component parts of the bones (phosphate of lime and magnesia) 
are absent, they satisfy the appetite without increasing the strength. — L. 



FALLOW-CROPS. 205 

injurious influence on corn which is cultivated immedi- 
ately after them is, that they do not extract the alkalies 
of the soil, and only a very small quantity of phosphates. 

It is evident that two plants growing beside each other 
will mutually injure one another, if they withdraw the 
same food from the soil. Hence it is not surprising that 
the Matricaria chamomiUa (Wild Chamomile) and Spar- 
Hum scoparium (Scotch Broom) impede the growth of 
corn, when it is considered that both yield from 7 to 
7.43 per cent, of ashes, which contain j% of carbonate 
of potash. The darnel, and the Erigeron acre (Flea- 
bane), blossom and bear fruit at the same time as 
the corn, so that when growing mingled with it, they will 
partake of the component parts of the soil, and in pro- 
portion to the vigor of their growth, that of the corn 
must decrease ; for what one receives, the others are de- 
prived of. Plants will, on the contrary, thrive beside 
each other, either when the substances necessary for their 
growth which they extract from the soil are of different 
kinds, or when they themselves are not both in the same 
stages of development at the same time. 

On a soil, for example, which contains potash, both 
wheat and tobacco may be reared in succession, because 
the latter plant does not require phosphates, salts which 
are invariably present in wheat, but requires only alkalies, 
and food containing nitrogen. 

According to the analysis of Posselt and Reimanriy 
10,000 parts of the leaves of the tobacco-plant contain 
16 parts of phosphate of lime, 8.8 parts of silica, and 
no magnesia ; whilst an equal quantity of wheat-straw 
contains 47.3 parts, and the same quantity of the grain 
of wheat 99.45 parts of phosphates. [De Saussure.) 

Now, if we suppose that the grain of wheat is equal 
18 



206 THE INTERCHANGE OF CROPS. 

to half the weight of its straw, then the quantity of phos- 
phates extracted from a soil by the same weights of 
wheat and tobacco must be as 97.7 : 16. This differ- 
ence is very considerable. The roots of tobacco, as 
well as those of wheat, extract the phosphates contained 
in the soil, but they restore them again, because they 
are not essentially necessary to the development of the 
plant. 



CHAPTER VIII. 

ON THE INTERCHANGE OP CROPS, AND OF MANURE. 

It has long since been found by experience, that the 
growth of annual plants is rendered imperfect, and their 
crops of fruit or herbs less abundant, by cultivating them 
in successive years on the same soil, and that, in spite 
of the loss of time, a greater quantity of grain is obtain- 
ed, when a field is allowed to be uncultivated for a year. 
During this interval of rest, the soil,* in a great measure, 
regains its original fertility. 

It has been further observed, that certain plants, such 
as peas, clover, and. flax, thrive on the same soil only 
after a lapse of years ; whilst others, such as hemp, to- 
bacco, helianthus tuberosus, rye, and oats, may be cul- 
tivated in close succession when proper manure is used. 
It has also been found, that several of these plants im- 
prove the soil, whilst others, and these are the most nu- 
merous, impoverish or exhaust it. Fallow turnips, cab- 
bage, beet, spelt, summer and winter barley, rye, and 
oats, are considered to belong to the class which impov- 
erish a soil ; whilst by wheat, hops, madder, late turnips. 



THEORIES OF ITS USE. 207 

hemp, poppies, teasel, flax, weld, and licorice, it is sup- 
posed to be entirely exhausted. 

The excrements of man and animals have been em- 
ployed from the earliest times for the purpose of increas- 
ing the fertility of soils ; and it is completely established 
by all experience, that they restore certain constituents 
to the soil which are removed with the roots, fruit, or 
grain, or entire plants grown upon it. 

But it has been observed that the crops are not al- 
ways abundant in proportion to the quantity of manure 
employed, even although it may have been of the most 
powerful kind ; that the produce of many plants, for 
example, diminishes, in spite of the apparent replace- 
ment of the substances removed from the soil by ma- 
nure, when they are cultivated on the same field for sev- 
eral years in succession. 

On the other hand it has been remarked, that a field 
which has become unfitted for a certain kind of plants 
was not on that account unsuited for another ; and upon 
this observation, a system of agriculture has been gradu- 
ally founded, the principal object of which is to obtain 
the greatest possible produce with the least expense of 
manure. 

Now it was deduced from all the foregoing facts that 
plants require for their growth different constituents of 
soil, and it was very soon perceived, that an alternation 
of the plants cultivated maintained the fertility of a soil 
quite as well as leaving it at rest or fallow. It was evi- 
dent that all plants must give back to the soil in which 
ihey grow different proportions of certain substances, 
which are capable of being used as food by a succeed- 
ing generation. 

But agriculture has hitherto never sought aid from 



208 THE INTERCHANGE OF CROPS. 

chemical principles, based on the knowledge of those 
substances which plants extract from the soil on which 
they grow, and of those restored to the soil by means of 
manure. The discovery of such principles will be the 
task of a future generation, for what can be expected 
from the present, which recoils with seeming distrust 
and aversion from all the means of assistance offered it 
by chemistry, and which does not understand the art of 
making a rational application of chemical discoveries ? 
A future generation, however, will derive incalculable 
advantage from these means of help. 

Of all the views which have been adopted regarding 
the cause of the favorable effects of the alternations of 
crops, that proposed by M. DecanJolIe alone deserves 
to be mentioned as resting on a firm basis. 

DecandoUe supposes that the roots of plants imbibe 
soluble matter of every kind from the soil, and thus 
necessarily absorb a number of substances which are 
not adapted to the purposes of nutrition, and must sub- 
sequently be expelled by the roots, and returned to the 
soil as excrements. Now as excrements cannot be as- 
similated by the plant which ejected them, the more of 
these matters which the soil contains, the more unfertile 
must it be for plants of the same species. These excre- 
mentitious matters may, however, still be capable of 
assimilation by another kind of plants, which would thus 
remove them from the soil, and render it aH,ain fertile 
for the first. And if the plants last grown also expel 
substances from their roots, which can be appropriated 
as food by the former, they will improve the soil in two 
ways. 

Now a great number of facts appear at first sight to 
give a high degree of probability to this view. Every 



THEORIES OF ITS USE. 209 

gardener knows that a fruit-tree cannot be made to grow 
on the same spot where another of the same species has 
stood ; at least not until after a lapse of several years. 
Before new vine-stocks are planted in a vineyard from 
which the old have been rooted out, other plants are 
cultivated on the soil for several years. In connexion 
with this it has been observed, that several plants thrive 
best when growing beside one another ; and on the con- 
trary, that others mutually prevent each other's devel- 
opment. Whence it was concluded, that the beneficial 
influence in the former case depended on a mutual inter- 
change of nutriment between the plants, and the injuri- 
ous one in the latter on a poisonous action of the excre- 
ments of each on the other respectively. 

A series of experiments by Alacaire-Princep gave 
great weight to this theory. He proved beyond all 
doubt that many plants are capable of emitting extractive 
matter from their roots. He found that the excretions 
were greater during the night than by day (?), and that 
the water in which plants of the family of the Legiimi- 
nosce grew, acquired a brown color. Plants of the 
same species, placed in water impregnated with these 
excrements, were impeded in their growth, and faded 
prematurely, whilst, on the contrary, corn-plants grew 
vigorously in it, and the color of the water diminished 
sensibly ; so that it appeared, as if a certainquantity of 
the excrements of the Leguminosce had really been ab- 
sorbed by the corn-plants. These experiments afforded 
as their main result, that the characters and properties 
of the excrements of different species of plants are dif- 
ferent from one another, and that some plants expel 
excrementitious matter of an acrid and resinous charac- 
ter ; others mild {douce) substances resembling gum. 
18* 



210 THE INTERCHANGE OF CROPS. 

The former of these, according to JMacnire-Princep, 
may be regarded as poisonous, the latter as nutritious. 

The experiments of Macaire-Princep are positive 
proof that the roots, probably of all plants, expel mat- 
ters, which cannot be converted in their organism 
either into woody fibre, starch, vegetable albumen, or 
gluten, since their expulsion indicates that they are 
quite unfitted for this purpose. But they cannot be 
considered as a confirmation of the theory of Decan- 
dolle, for they leave it quite undecided whether the sub- 
stances were extracted from the soil, or formed by the 
•plant itself from food received from another source. It 
•is certain that the gummy and resinous excrements ob- 
served by Macaire-Princep could not have been con- 
tained in the soil ; and as we know that the carbon of a 
soil is not diminished by culture, but, on the contrary, 
increased, we must conclude, that all excrements which 
contain carbon must be formed from the food obtained 
by plants from the atmosphere. Now, these excre- 
ments are compounds, produced in consequence of the 
transformations of the food, and of the new forms which 
it assumes by entering into the composition of the vari- 
ous organs. 

M. Decandol/e^s theory is properly a modification of 
an earlier hypothesis, which supposed that the roots of 
different plants extracted different nutritive substances 
from the soil, each plant selecting that which was ex- 
actly suited for its assimilation. According to this 
hypothesis, the matters incapable of assimilation are not 
extracted from the soil, whilst M. Decandolle considers 
that they are returned to it in the form of excrements. 
Both views explain how it happens that after corn, corn 
cannot be raised with advantage, nor after peas, peas ; 



THEORIES OF ITS USE. 211 

but they do not explain how a field is improved by ly- 
ing fallow, and this in proportion to the care with which 
it is tilled and kept free from weeds ; nor do they show 
how a soil gains carbonaceous matter by the cultivation 
of certain plants, such as lucern and esparsette. 

Theoretical considerations on the process of nutrition, 
as well as the experience of all agriculturists, so beau- 
tifully illustrated by the experiments of Macaire-Prin- 
cep^ leave no doubt that substances are excreted from 
the roots of plants, and that these matters form the 
means by which the carbon received from humus in the 
early period of their growth, is restored -to the soil. 
But we may now inquire whether these excrements in 
the state in which they are expelled, are capable of be- 
ing employed as food by other plants. 

The excrements of a carnivorous animal contain no 
constituents fitted for the nourishment of another of the 
same species ; but it is possible that an herbivorous an- 
imal, a fish, or a fowl, might find in them undigested 
matters, capable of being digested in their organism, 
from the very circumstance of their organs of digestion 
having a different structure. This is the only sense in 
which we can conceive that the excrements of one ani- 
mal could yield matter adapted for the nutrition of an- 
other. 

A number of substances contained in the food of 
animals pass through their alimentary organs without 
change, and are expelled from the system ; these are 
excrements but not excretions. Now a part of such 
excrementitious matter might be assimilated in passing 
through the digestive apparatus of another animal. Th** 
organs of secretion form combinations of which only the 
elements were contained in the food. The production 



212 THE INTERCHANGE OF CROPS. 

of these new compounds is a consequence of the 
changes which the food undergoes in becoming chyle 
and chyme, and of the further transformations to which 
these are subjected by entering into the composition of 
the organism. These matters, hkewise, are ehminated in 
the excrements, which must therefore consist of two dif- 
ferent kinds of substances, namely, of the indigestible 
constituents of the food, and of the new compounds 
formed by the vital process. The latter substances have 
been produced in consequence of the formation of fat, 
muscular fibre, cerebral and nervous substance, and are 
quite incapable of being "converted into the same sub- 
stances in any other animal organism. 

Exactly similar conditions must subsist in the vital 
processes of plants. When substances, wliich are inca- 
pable of being employed in the nutrition of a plant, ex- 
ist in the matter absorbed by its roots, they must be 
again returned to the soil. Such excrements might be 
serviceable and even indispensable to the existence of 
several other plants. But substances that are formed in 
a vegetable organism during the process of nutrition, 
which are produced, therefore, in consequence of the 
formation of woody fibre, starch, albumen, gum, acids, 
&ic., cannot again serve in any other plants to form the 
same constituents of vegetables. 

The consideration of these facts enables us to distin- 
guish the difference between the views of DccandoUe 
and those of Macaire-Princep. The substances which 
the former physiologist viewed as excrements, belonged 
to the soil ; they were undigested matters, which, al- 
though not adapted for the nutrition of one plant, might 
yet be indispensable to another. Those matters, on 
the contrary, designated as excrements by Macaire- 



CAUSES OF ITS BENEFICIAL INFLUENCE. 213 

Princep^ could only in one form serve for the nutrition 
of vegetables. It is scarcely necessary to remark, that 
this excrementitious matter must undergo a change be- 
fore another season. During autumn and winter it begins 
to suffer a change from the influence of air and water ; 
its putrefaction, and at length, by continued contact with 
the air, which tillage is the means of procuring, its de- 
cay are effected ; and at the commencement of spring 
it has become converted, either in whole or in part, into 
a substance which supplies the place of humus, by be- 
ing a constant source of carbonic acid. 

The quickness with which this decay of the excre- 
ments of plants proceeds, depends on the composition 
of the soil, and on its greater or less porosity. It will 
take place very quickly in a calcareous soil ; for the 
power of organic excrements to attract oxygen and to 
putrefy is increased by contact with the alkaline constit- 
uents, and by the general porous nature of such kinds 
of soil, which freely permit the access of air. But it 
requires a longer time in heavy soils consisting of loam 
or clay. 

The same plants can be cultivated with advantage on 
one soil after the second year, but in others not until the 
fifth or ninth, merely on account of the change and de- 
struction of the excrements which have an injurious in- 
fluence on the plants being completed in the one, in the 
second year ; in the others, not until the ninth. 

In some neighbourhoods, clover will not thrive till 
the sixth year ; in others not till the twelfth ; flax in the 
second or third year. All this depends upon the chem- 
ical nature of the soil ; for it has been found by expe- 
rience, that in those districts where the intervals at 
which the same plants can be cultivated with advantage, 



214 THE INTERCHANGE OF CROPS. 

are very long, the time cannot be shortened even by the 
use of the most powerful manures. The destruction of 
the peculiar excrements of one crop must have taken 
place before a new crop can be produced. 

Flax, peas, clover, and even potatoes, are plants the 
excrements of which, in argillaceous soils, require the 
longest time for their conversion into humus ; but it is 
evident, that the use of alkalies and burnt lime, or even 
small quantities of ashes which have not been lixiviated, 
must enable a soil to permit the culivation of the same 
plants in a much shorter time. 

A soil lying fallow owes its earlier fertility, in part, to 
the destruction or conversion into humus of the excre- 
ments contained in it, which is effected during the fallow 
season, at the same time that the land is exposed to a 
further disintegration. 

In the soils in the neighbourhood of the Rhine and 
Nile, which contain much potash, and where crops can 
be obtained in close succession from the same field, the 
fallowing of the land is superseded by the inundation ; 
the irrigation of meadows effects the same purpose. It 
is because the water of rivers and streams contains oxygen 
in solution, that it effects the most complete and rapid 
putrefaction of the excrements contained in the soil 
which it penetrates, and in which it is continually re- 
newed. If it was the water alone which produced this 
effect, marshy meadows should be the most fertile. 

It follows from what has preceded, that the advantage 
of the alternation of crops is owing to two causes. 

A fertile soil ought to afford to a plant all the inorganic 
bodies indispensable for its existence in sufiicient quan- 
tity and in such condition as allows their absorption. 

All plants require alkalies, which are contained in 



CAUSES OF ITS BENEFICIAL INFLUENCE. 215 

some, in the graminece for example, in the form of sili- 
cates, in others, in that of tartrates, citrates, acetates, 
or oxalates. 

When these alkalies are in combination with silicic 
acid, the ashes obtained by the incineration of the plant 
contain no carbonic acid ; but when they are united with 
organic acids, the addition of a mineral acid to their 
ashes causes an effervescence. 

A third species of plants requires phosphate of lime, 
another, phosphate of magnesia, and several do not thrive 
without carbonate of lime. 

Silicic acid * is the first solid substance taken up by 
plants ; it appears to be the material from which the 

* Silica, or siliceous earth is the most abundant ingredient in the 
mineral kingdom, being one of the constituents of most rocks, and 
extensively distributed over the earth in the form of sand, quartz, 
carnelian, flint, &c., &c. It is also held in solution by the water 
of hot springs, as in the Geysers of Iceland, and the Azores, from 
which it is deposited, forming what is called siliceovs sinter, and often 
encrusting the stems of plants and other bodies. The vegetable mat- 
ter in some instances has entirely disappeared, and the silica having 
taken its place we have silicified or petrified wood, &c. See Webster's 
Description of the Island of St. Michael, p. 208. From silcia a sub- 
stance is obtained which is considered as its base, and called silicon 
and silicivm. This base combined with oxygen, constitutes silica, 
which is capable of combining with other bases; from this and other 
properties it is called silicic acid. By combination with other sub- 
stances, as potash, soda, &c , silica becomes soluble in water. These 
compounds are called silicates. A while, earthy substance is found 
beneath peat and in swampy land and ponds, which has long been 
mistaken for calcareous marl. It has been proved to consist of the 
siliceous skeletons of " infusorial vegetables, if they may be so called, 
or of those equivocal beings which occupy the borders of the two 
kingdoms, and render it difficult, not to say impossible, to draw the 
line between them." This siliceous deposit has been found under 
nearly every peat bog in this country which has been examined. See 
Professor Bailey's paper in American Journal of Science, Vol. XXXV. 
p. 118, and Vol. XL. p. 174. 



216 THE INTERCHANGE OF CROPS. 

formation of the wood lakes its origin, acting like a grain 
of sand around which the first crystals form in a solution 
of a salt which is in the act of crystallizing. Silicic 
acid appears to perform the function of woody fibre in 
the EquisetacecB and bamboos, just as the crystalline 
salt, oxalate of lime, does in many of the lichens. 

When we grow in the same soil for several years 
in succession different plants, the first of which leaves 
behind that which the second, and the second that which 
the third may require, the soil will be a fruitful one for 
all the three kinds of produce. If the first plant, for 
example, be wheat, which consumes the greatest part of 
the silicate of potash in a soil, whilst the plants which 
succeed it are of such a kind as require only small quan- 
tities of potash, as is the case with the Legmninosce, 
turnips, potatoes, &c. ; the wheat may be again sowed 
with advantage after the fourth year ; for, during the in- 
terval of three years, the soil will, by the action of the 
atmosphere, be rendered capable of again yielding silicate 
of potash in sufl!icient quantity for the young plants. 

The same precautions must be observed with regard 
to the other inorganic constituents, when it is desired to 
grow different plants in succession on the same soil ; for 
a successive growth of plants which extract the same 
component parts, must gradually render it incapable of 
producing them. Each of these plants, during its growth, 
returns to the soil a certain quantity of substances con- 
taining carbon, which are gradually converted into humus, 
and are for the most part equivalent to as much carbon 
as the plants had formerly extracted from the soil in the 
state of carbonic acid. But although this is sufiicient 
to bring many plants to maturity, it is not enough to 
furnish their different organs with the greatest possible 



CAUSES OF ITS BENEFICIAL INFLUENCE. 217 

supply of nourishment. Now the object of agriculture 
is to produce either articles of commerce, or- food for 
man and animals, but a maximum of produce in plants is 
always in proportion to the quantity of nutriment supplied 
to them in the first stage of their development. 

The nutriment of young plants consists of carbonic 
acid, contained in the soil in ihe form of humus, and 
of nitrogen in the form of ammonia, both of which must 
be supplied to the plants if the desired purpose is to be 
accomplished. The formation of ammonia cannot be 
effected on cultivated land, but humus may be artificially 
produced ; and this must be considered as an important 
object in the alternation of crops, and as the second reason 
of its peculiar advantages. 

The sowing of a field with fallow plants, such as 
clover, rye, buck-wheat, &c. and the incorporation of 
the plants, when nearly at blossom, with the soil, affect 
this supply of humus in so far, that young plants subse- 
qently growing in it find, at a certain period of their 
growth, a maximum of nutriment, that is, matter ig the 
process of decay. 

The same end is obtained, but with much greater 
certainty, when the field is planted with esparsette (sain- 
foin) or lucern. These plants are remarkable on account 
of the great ramification of their roots, and strong devel- 
opment of their leaves, and for requiring only a small; 
quantity of inorganic matter. Until they reach a certain 
period of their growth, they retain all the carbonic acid 
and ammonia which may have been conveyed to them 
by rain and the air, for that which is not absorbed by the 
soil is appropriated by the leaves : they also possess an 
extensive four or six fold surface capable of assimilating 
19 



218 THE INTERCHANGE OF CROPS. 

these bodies, and of preventing the volatih'zation of the 
ammonia from the soil, by completely covering it in. 

An immediate consequence of the production of the 
green principle of the leaves, and of their remaining 
component parts, as well as of those of the stem, is the 
equally abundant excretion of organic matters into the 
soil from the roots. 

The favorable influence which this exercises on the 
land, by furnishing it with matter capable of being con- 
verted into humus lasts for several years, but barren 
spots gradually appear after the lapse of some time. 
Now, it is evident, that after from six to seven years the 
ground must become so impregnated with excrements 
that every fibre of the root will be surrounded with 
them. As they remain for some lime in a soluble con- 
dition, the plants must absorb part of them and suffer 
injurious effects in consequence, because they are not 
capable of assimilation. When such a field is observed 
for several years, it is seen, that the barren spots are 
again covered with vegetation, (the same plants being 
always supposed to be grown,) whilst new spots become 
bare and apparently unfruitful, and so on alternately. 
The causes which produce this alternate barrenness and 
fertility in the different parts of the land are evident. 
The excrements upon the barren spots receiving no 
new addition, and being subjected to the influence of 
air and moisture, they pass into putrefaction, and their 
injurious influence ceases. The plants now find those 
substances, which formerly prevented their growth re- 
moved, and in their place meet with humus, that is, 
vegetable matter in the act of decay. 

We can scarcely suppose a better means of produ- 
cing humus than by the growth of plants, the leaves of 



CAUSES OF ITS BENEFICIAL INFLUENCE. 219 

which are food for animals ; for they prepare the soil 
for plants of every other kind, but particularly for those 
to which, as to rape and flax, the presence of humus is 
the most essential condition of growth. 

The reasons why this interchange of crops is so ad- 
vantageous, — the principles which regulate this part of 
agriculture, are, therefore, the artificial production of 
humus, and the cultivation of different kinds of plants 
upon the same field, in such an order of succession, 
that each shall extract only certain components of the 
soil, whilst it leaves behind or restores those which a 
second or third species of plant may require for its 
growth and perfect development. 

Now, although the quantity of humus in a soil may be 
increased to a certain degree by an artificial cultivation, 
still, in spite of this, there cannot be the smallest doubt 
that a soil must gradually lose those of its constituents 
which are removed in the seeds, roots, and leaves of 
the plants raised upon it. The fertility of a soil cannot 
remain unimpaired, unless we replace in it all those 
substances of which it has been thus deprived. 

Now this is effected by manure. 

When it is considered that every constituent of the 
body of man and animals is derived from plants, and 
that not a single element is generated by the vital prin- 
ciple, it is evident that all the inorganic constituents of 
the animal organism must be regarded, in some respect 
or other, as manure. During their life, the inorganic 
components of plants which are not required by the 
animal system, are disengaged from the organism, in the 
form of excrements. After their death, their nitrogen 
and carbon pass into the atmosphere as ammonia and 
carbonic acid, the products of their putrefaction, and at 



220 OF MANURE. 

last nothing remains except the phosphate of lime and 
other salts in their bones.* Now this earthy residue of 
the putrefaction of animals must be considered in a ra- 
tional system of agriculture, as a powerful manure for 
plants, because that which has been abstracted from a 
soil for a series of years must be restored to it, if the 
land is to be kept in a permanent condition of fertility. 

We may now inquire whether the excrements of an- 
imals, which are employed as manure, are all of a like 
nature and power, and whether they, in every case, ad- 
minister to the necessities of a plant by an identical 
mode of action. These points may easily be deter- 
mined by ascertaining the composition of the animal 
excrements, because we shall thus learn what substances 
a soil really receives by their means. According to 
the common view, the action of solid animal excrements 
depends on the decaying organic matters which replace 
the humus, and on the presence of certain compounds 
of nitrogen, which are supposed to be assimilated by 
plants, and employed in the production of gluten and 
other azotized substances. But this view requires fur- 
ther confirmation with respect to the solid excrements 
of animals, for they contain so small a proportion of 
nitrogen, that they cannot possibly by means of it exer- 
cise any influence upon vegetation. 

We may form a tolerably correct idea of the chem- 
ical nature of animal excrement without further exami- 
nation, by comparing the excrements of a dog with its 
food. When a dog is fed with flesh and bones, both of 
which consist in great part of organic substances con- 
taining nitrogen, a moist white excrement is produced 

* See note, p. 202. 



COMPOSITION OF ANIMAL MANURES. 221 

which crumbles gradually to a dry powder in the air. 
This excrement consists of the posphate of lime of the 
bones, and contains scarcely ^ig part of its weight of 
foreign organic substances. The whole process of nu- 
trition in an animal consists in the progressive extrac- 
tion of all the nitrogen from the food, so that the quan- 
tity of this element found in the excrements must always 
be less than that contained in the nutriment. The 
analysis of the excrements of a horse by Macaire and 
Marcet proves this fact completely. The portion of 
excrements subjected to analysis was collected whilst 
fresh, and dried in vacuo over sulphuric acid ; 100 parts 
of it (corresponding to from 350 to 400 parts of the 
dung before being dried) contained 0.8 of nitrogen. 
Now every one who has had experience in this kind of 
analysis is aware that a quantity under one per cent, 
cannot be determined with accuracy. We should, 
therefore, be estimating its proportion at a maximum, 
were we to consider it as equal to one half per cent. 
It is certain, however, that these excrements are not 
entirely free from nitrogen, for they emit ammonia when 
digested with caustic potash. 

The excrements of a cow, on combustion with oxide 
of copper, yielded a gas which contained one vol. of 
nitrogen gas, and 26.30 vol. of carbonic acid. 

100 parts of fresh excrements contained. 

Nitrogen, 0.506 

Carbon, 6.204 

Hydrogen, 0.824 

Oxygen, 4.818 

Ashes, 1.748 

Water, , ... . . . 85.900 

100.000 
19* 



222 OF MANURE. 

Now, according to the analysis of Boussingault, 
which merits the greatest confidence, hay contains one 
per cent, of nitrogen ; consequently in the 25 lbs. of 
hay which a cow consumes daily, | of a lb. of nitrogen 
must have been assimilated. This quantity of nitrogen 
entering into the composition of muscular fibre would 
yield 8.3 lbs. of flesh in its natural condition.* The 
daily increase in size of a cow is, however, much less 
than this quantity. We find that the nitrogen, appar- 
ently deficient, is actually contained in the milk and 
urine of the animal. The urine of a milch-cow contains 
Jess nitrogen than that of one which does not yield 
milk ; and as long as a cow yields a plentiful supply of 
milk, it cannot be fattened. We must search for the 
nitrogen of the food assimilated not in the solid, but in 
the liquid excrements. The influence which the former 

* 100 lbs. of flesh contain on an average 15.86 of muscular fibre : 
18 parts of nitrogen are contained in TOO parts of the latter. — L. 

The flesh of animals when digested in repeated portions of cold 
water, affords albumen, saline substances, and coloring and extractive 
matters. When the part that is no longer acted on by cold water is 
digested in hot water, the cellular substance is removed in the form 
of selatine, and fatty matter separates. The insoluble residue is prin- 
cipally Jibrinc. 

The following is the proportion of water, albumen, and gelatine in 
the muscular parts of several animals and fishes. 



100 parts of 




Albumen or 




Total of 


Muscle of 


Water. 


Fibrine. 


Gelatine. 


JV^utritive 


Matter. 


Beef, 


74 


20 


6 




26 


Veal, 


75 


19 


6 




25 


Mutton, 


71 


22 


7 




29 


Pork, 


76 


19 


5 




24 


^Chicken, 


73 


20 


7 




27 


Cod, 


79 


14 


7 




21 


Haddock, 


82 


13 


5 




18 



See Brande's Chemistry, 4th edit. p. 1184. 



ITS ESSENTIAL ELEMENTS. 223 

exercise on the growth of vegetables does not depend 
upon the quantity of nitrogen which they contain. For 
if this were the case, hay should possess the same in- 
fluence ; that is, from 20 to 25 lbs. ought to have the 
same power as 100 lbs. of fresh cow-dung. But this 
is quite opposed to all experience. 

Which then are the substances in the excrements of 
the cow and horse which exert an influence on vegeta- 
tion ? 

When horse's dung is treated with water, a portion 
of it to the amount of 3 or 3| per cent, is dissolved, and 
the water is colored yellow. The solution is found to 
contain phosphate of magnesia, and salts of soda, be- 
sides small quantities of organic matters. The portion 
of the dung undissolved by the water yields to alcohol 
a resinous substance possessing all the characters of gall 
which has undergone some change ; while the residue 
possesses the properties of sawdust, from which all sol- 
uble matter has been extracted by water, and burns 
without any smell. 100 parts of the fresh dung of a horse 
being dried at 100° C (212° F.) leave from 25 to 30 or 
31 parts of solid substances, and contained, accordingly, 
from 69 to 75 parts of water. From the dried excre- 
ments, we obtain, by incineration, variable quantities of 
salts and earthy matters according to the nature of the 
food which has been taken by the animal. Macaire 
and Marcet found 27 per cent, in the dung analyzed by 
them ; I obtained only 10 per cent, from that of a horse 
fed with chopped straw, oats, and hay. It results then 
that with from 3,600 to 4,000 lbs. of fresh horse's dung, 
corresponding to 1,000 lbs. of dry dung, we place on 
the land from 2,484 to 3,000 lbs. of water, and from 
730 to 900 lbs. of vegetable and altered gall, and also 



224 OF MANURE. 

from 100 to 270 lbs. of salts and other inorganic sub- 
stances.* 

The latter are evidently the substances to which our 
attention should be directed, for they are the same which 
formed the component parts of the hay, straw, and 
oats, with which the horse was fed. Their principal 
constituents are the phosphates of lime and magnesia, 
carbonate of lime and silicate of potash ; the first three 
of these preponderated in the corn, the latter in the 
hay. 

Thus in 1,000 lbs. of horse's dung, we present to a 
field the inorganic substances contained in 6,000 lbs. of 
hay, or 8,300 lbs. of oats (oats containing 3.1 per cent, 
ashes according to De Saussure). This is sufficient 
to supply lA crop of wheat with potash and phos- 
phates. 

* Analysis of horse dung by Dr. C. T. Jackson. — 500 grains dried 

at a heat a little above that of boiling water, lost 357 grains, which 

was water. 
The dry mass, weighing 143 grains, was burned, and left 8.5 grains 

of ashes, of which 4.80 grains were soluble in dilute nitric acid, and 

3.20 insoluble. The ashes being analyzed, gave, — 
Silex, . . . . . 3.2 

Phosphate of lime, . . . 0.4 

Carbonate of ••' . . . 1.5 

Phos. magnesia and soda, . 2.9 

8.0 

It consists, then, of the following ingredients : 

Water, 357.0 

Vegetable fibre and animal matter, 135.0 

Silica, 3.2 

Phosphate of lime, .... 0.4 
Carbonate of " . . . . 1.5 

Phos. magnesia and soda, . . . 2.9 



500.0 
Geological and Agricultural Survey of Rhode Island, p. 205. 



ITS ESSENTIAL ELEMENTS. 225 

The excrements of cows, black cattle, and sheep, 
contain phosphate of lime, common salt, and silicate 
of lime, the weight of which varies from 9 to 28 per 
cent, according to the fodder which the animal receives ; 
the fresh excrements of the cow contain from 86 to 90 
per cent, of water. 

Human faeces have been subjected to an exact analy- 
sis by BerzcKus. When fresh, they contain, besides 4 
of their weight of water, nitrogen in very variable quan- 
tity, namely, in the minimum Ij, in the maximum 5 
per cent. In all cases, however, they were richer 
in this element than were the excrements of other ani- 
mals. Bcrzelius obtained by the incineration of 100 
parts of dried excrements, 15 parts of ashes, which 
were principally composed of the phosphates of lime 
and magnesia. 

It is quite certain that the vegetable constituents of 
the excrements with which we manure our fields cannot 
be entirely without influence upon the growth of the 
crops on them, for they will decay, and thus furnish car- 
bonic acid to the young plants. But it cannot be im- 
agined that their influence is very great, when it is con- 
sidered that a good soil is manured only once every six 
or seven years, or once every eleven or twelve years, 
when esparsette or lucern have been raised on it, that 
the quantity of carbon thus given to the land corresponds 
to only 5.8 per cent, of what is removed in the form of 
herbs, straw, and grain, and further, that the rain-water 
received by a soil contains much more carbon in the 
form of carbonic acid than these vegetable constituents 
of the manure. 

The peculiar action, then, of the solid excrements is 
limited to their inorganic constituents, which thus re- 



226 OF MANTTRE, 

Store to a soil that which is removed in the form of corn, 
roots, or grain. When we manure land with the dung 
of the cow or sheep, we supply it with silicate of pot- 
ash and some salts of phosphoric acid. In human fseces 
we give it the phosphates of lime and magnesia ; and in 
those of the horse, phosphate of magnesia, and silicate 
of potash. In the straw which has served as litter, we 
add a further quantity of silicate of potash and phos- 
phates ; which, if the straw be putrefied, are in exactly 
the same condition in which they were before being as- 
similated. 

It is evident, therefore, that the soil of a field will al- 
ter but little, if we collect and distribute the dung care- 
fully ; a certain portion of the phosphates, however, 
must be lost every year, being removed from the land 
with the corn and cattle, and this portion will accumu- 
late in the neighbourhood of large towns. The loss thus 
suffered must be compensated for in a well managed 
farm, and this is partly done by allowing the fields to lie 
in grass. In Germany, it is considered that for every 
100 acres of corn land, there must, in order to effect a 
profitable cultivation, be 20 acres of pasture land, which 
produce annually, on an average, 500 lbs. of hay. Now, 
assuming that the ashes of the excrements of the animals 
fed with this hay amount to G.82 per cent., then 341 
lbs. of the silicate of lime, and phosphates of magnesia 
and lime must be yielded by these excrements, and will 
in a certain measure compensate for the loss which the 
corn land had sustained. The absolute loss in the salts 
of phosphoric acid, which are not again rej)laced, is 
spread over so great an extent of surface, that it scarce- 
ly deserves to be taken account of. But the loss of 



ITS ESSENTIAL ELEMENTS. 227 

phosphates is again replaced in the pastures by the ashes 
of the wood used in our houses for fuel. 

We could keep our fields in a constant state of fer- 
tility by replacing every year as much as we remove 
from them in the form of produce ; but an increase of 
fertility, and consequent increase of crop, can only be 
obtained when we add more to them than we take away. 
It will be found, that of two fields placed under condi- 
tions otherwise similar, the one will be most fruitful 
upon which the plants are enabled to appropriate more 
easily and in greater abundance those contents of the 
soil which are essential to their growth and development. 

From the foregoing remarks it will readily be inferred, 
that for animal excrements, other substances containing 
their essential constituents may be substituted. In 
Flanders, the yearly loss of the necessary matters in 
the soil is completely restored by covering the fields 
with ashes of wood or bones, which may or may not 
have been lixiviated,* and of which the greatest part 
consists of of phosphates of lime and magnesia. The 
great importance of manuring with ashes has been long 
recognised by agriculturists as the result of experi- 
ence. So great a value, indeed, is attached to this ma- 
terial in the vicinity of Marburg, and in the Wetterau,f 
that it is transported as a manure from the distance of 18 
or 24 miles. I Its use will be at once perceived, when it 

* Lixiviation signifies the removal by water of the soluble alkaline 
or saline matters in any earthy mixture; as from that of lime and pot- 
ash, or from ashes to obtain a ley. 

t Two well-known agiicultuial districts; the first in Hesse-Cassel, 
the second in Hesse-Darmstadt. — Trans. 

I Ashes are used with great advantage on the light siliceous soil of 
Long Island, Connecticut, and various other places in the United 
States. 



228 OF MANURE. 

is considered that the ashes, after having been washed 
with water, contain sihcate of potash exactly in the same 
proportions as in straw (10 Si O 3 + K O), and that 
their only other constituents are salts of phosphoric acid. 

But ashes obtained from various kinds of trees are of 
very unequal value for this purpose ; those from oak- 
wood are the least, and those from beech the most ser- 
viceable. The ashes of oak-wood contain only traces 
of phosphates, those of beech the fifth part of their 
weight, and those of the pine and fir from 9 to 15 per 
cent. The ashes of pines from Norway contain an ex- 
ceedingly small quantity of phosphates, namely, only 1.8 
per cent, of phosphoric acid. (Berthier.)* 

With every 100 lbs. of the lixiviated ashes of the 
beech which we spread over a soil, we furnish as much 
phosphates as 460 lbs. of fresh human excrements could 
yield. Again, according to the analysis of De Saussure, 
100 parts of the ashes of the grain of wheat contain 32 
parts of soluble, and 44.5 of insoluble phosphates, in all 

* " The existence of pliosphate of litne in the forest soils of the 
United States, is proved not only by its existence in the pollen of the 
pinus ubics (which is composed of 3 per cent, phosphate of lime 
and potash), but by its actual detection in the ashes of pines and 
other trees. — 100 parts of the ashes of wood of pinus dbies give 3 
per cent, phosphate of iron ; 100 parts of the ashes of the coal of 
pinus sylvestris give 1.72 phosphate of lime, 25 phosphate of iron ; 
100 parts of ashes of oak coal give 7.1 phosphate of lime, 3.7 phos- 
phate of iron ; 100 parts of the ashes of bass wood give 5.4 phosphate 
of lime, 3.2 phos^jhate of iron ; 100 parts of the ashes of birch wood 
give 7.3 pliosphate of lime, 1.25 phosphate of iron ; 100 parts of the 
ashes of oak wood give 1.8 phosphate of lime ; 100 parts of the ashes 
of alder coal give 3.-15 phosphate of lime, 9 phosphate of iron. These 
are the calculated results from Certhier's analyses." — Dr. S. L. Dana 
in Report on a Reexamination of the Economical Geology of Mas- 
sachusetts. 



BONE MANURE. 229 

76.5 parts. Now the ashes of wheat-straw contain 11.5 
per cent, of the sanne salts ; hence with every 100 lbs. of 
the ashes of the beech, we supply a field with phos- 
phoric acid sufficient for the production of 3,820 lbs. of 
straw (its ashes being calculated at 4.3 per cent. De 
Saussure), or for 15-lSOOO lbs. of corn, the ashes of 
which amount, according to De Saussure, to 1.3 per 
cent. 

Bone manure possesses a still greater importance in 
this respect. The primary sources from which the bones 
of animals are derived are the hay, straw, or other sub- 
stances which they take as food. Now if we admit that 
bones contain 55 per cent, of the phosphates of lime 
and magnesia [Berzellus)^ and that hay contains as much 
of them as wheat-straw, it will follow that 8 lbs. of bones 
contain as much phosphate of lime as 1,000 lbs. of hay 
or wheat-straw, and 2 lbs. of it as much as 1,000 lbs. of 
the grain of wheat or oats. These numbers express 
pretty exactly the quantity of phosphates which a soil 
yields annually on the growth of hay and corn. Now 
the manure of an acre of land with 40 lbs. of bone dust 
is sufficient to supply three crops of wheat, clover, po- 
tatoes, turnips, &c., with phosphates. But the form in 
which they are restored lo a soil does not appear to 
be a matter of indifference. For the more finely the 
bones are reduced to powder, and the more intimately 
they are mixed with a soil, the more easily are they 
assimilated. The most easy and practical mode of ef- 
fecting their division is to pour over the bones, in a state 
of fine powder, half of their weight of sulphuric acid 
diluted with three or four parts of water, and after they 
have been digested for some time, to add one hundred 
parts of water, and sprinkle this mixture over the field. 
20 



230 OF MANURE. 

before the plough. In a few seconds, the free acids unite 
with the bases contained in the earth, and a neutral salt is 
formed in a very fine state of division. Experiments 
instituted on a soil formed from grauvvacke, for the pur- 
pose of ascertaining the action of manure thus prepared, 
have distinctly shown that neither corn, nor kitchen- 
garden plants, suffer injurious effects in consequence, 
but that on the contrary they thrive with much more 
vigor. 

In the manufactories of glue, many hundred tons of a 
solution of phosphates in muriatic acid are yearly thrown 
away as being useless. It would be important to exam- 
ine whether this solution might not be substituted for the 
bones. The free acid would combine with the alkalies 
in the soil, especially with the lime, and a soluble salt 
would thus be produced, which is known to possess a 
favorable action upon the growth of plants. This salt, 
muriate of lime (or chloride of calcium), is one of those 
compounds which attracts water from the atmosphere 
with great avidity, and might supply the place of gypsum 
in decomposing carbonate of ammonia, with the forma- 
tion of sal-ammoniac and carbonate of lime. A solution 
of bones in muriatic acid placed on land in autumn or in 
winter would, therefore, not only restore a necessary 
constituent of the soil, and attract moisture to it, but 
would also give it the power to retain all the ammonia 
which fell upon it dissolved in the rain during the period 
of six months. 

The ashes of brown coal* and peat often contain sili- 

* Brown coal. Braunkohlc, Lignite has the structure and appear- 
ance of carbonized wood. It occurs abundantly in Germany ; in 
Hessia it forms beds 20 to 40 feet thick, and several square miles in 



ASHES. PEAT. 231 

catG of potash, so that it is evident that these might com- 
pletely replace one of the principal constituents of the 
dung of the cow and horse, and they contain also some 
phosphates.* Indeed, they are much esteemed in the 
Wetterau as manure for meadows and moist land. 

extent. Fibrous and compact varieties occur near Bovey Tracey in 

England, where it is called Bovey coal. Small quantities are found 

at Gay Head, Massachusetts. 

* The following is the result of an analysis by Dr. C. T. Jackson, 

of peat from Lexington, Massachusetts. 100 grains, dried at 300° F. 

weighed 74 grains, loss 26 grains, water. Buined in a platina crucible 

it left 5.0 ashes. The ashes yielded 

Silex, 10 

Alumina, iron, and manganese, .... 0.6 

Phosphate of lime, 3.0 

Potash, traces. 

4.6 

Peat from Watertown, Massachusetts, yielded 4.5 grains of ashes, 

which gave by analysis 

Silex, ........ 1.3 

Alumina, oxide of iron, and manganese, . . 1.5 

Phosphate of lime, 1.7 

4.5 

The vegetable matter amounted to 95.5 per cent., consisting of 
veo-etable fibre, and apocrenic and crenic acids, in part combined with 
the bases obtained from its ashes. See Report on Rhode Island, 
p. 233. 

Swamp muck contains the same ingredients as peat, but the vege- 
table matters are more finely divided, more soluble, and there is gen- 
erally a larger proportion of earthy matters. It is formed of the fine 
particles of humus, washed out from the upland soils, and of the dead 
and decomposed leaves and roots of swamp plants. 

The pulpy matter of both peat and swamp muck consists chiefly of 
the apocrenic acid, in part combined with the earthy bases, and me- 
tallic oxides. The crenic acid is frequently united with lime, man- 
ganese ; iron and magnesia occur in several of the peats analyzed. 
Phosjihoric acid also exists in them, both in its free state, and in com- 
bination with lime and magnesia. In some peats Dr. J. found traces 
of oxalic acid and oxalates. Ibid., 210. See Appendix for Peat com- 
post. 



232 OF MANURE. 

It is of much importance to the agriculturist, that he 
should not deceive himself respecting the causes which 
give the peculiar action to the substances just men- 
tioned. It is known that they possess a very favorable 
influence on vegetation ; and it is likewise certain, that 
the cause of this is their containing a body, which, in- 
dependently of the influence which it exerts by virtue of 
its form, porosity, and capability of attracting and re- 
taining moisture, also assists in maintaining the vital 
processes in plants. If it be treated as an unfathoma- 
ble mystery, the nature of this aid will never be known. 

In medicine, for many centuries, the mode of actions 
of all remedies was supposed to be concealed by the 
mystic veil of Isis, but now these secrets have been ex- 
plained in a very simple manner. An unpoetlcal hand 
has pointed out the cause of the wonderful and apparent- 
ly inexplicable healing virtues of the springs in Savoy, 
by which the inhabitants cured their goitre ; it was 
shown, that they contain small quantities of iodine. In 
burnt sponges, used for the same purpose, the same ele- 
ment was also detected. The extraordinary efficacy of 
Peruvian bark was found to depend on the small quanti- 
ty of a crystalline body existing in it, viz. quinine ; and 
the causes of the various effects of opium were detect- 
ed in as many different ingredients of that drug. 

Calico printers used for a long time the solid excre- 
ments of the cow, in order to brighten and fasten colors 
on cotton goods ; this material appeared quite indispen- 
sable, and its action was ascribed to a latent principle 
which it had obtained from the living organism. But 
since its action was known to depend on the phosphates 
contained in it, it has been completely replaced by a 



PRINCIPLES OF ITS USE. 233 

mixture of salts, in which the principal constituent is 
phosphate of soda. 

Now, all such actions depend on a definite cause, by 
ascertaining which, we place the actions themselves at 
our command. 

It must be admitted as a principle of agriculture, that 
those substances which have been removed from a soil 
must be completely restored to it, and whether this res- 
toration be effected by means of excrements, ashes, or 
bones, is in a great measure a matter of indifference. 
A time will come when fields will be manured with a 
solution of glass* (silicate of potash), with the ashes of 
burnt straw, and with salts of phosphoric acid, prepared 
in chemical manufactories, exactly as at present medi- 
cines are given for fever and goitre. 

There are some plants which require humus and do not 
restore it to the soil by their excrements ; whilst others 
can do without it altogether, and add humus to a soil 
which contains it in small quantity. Hence, a rational 
system of agriculture would employ all the humus at 
command for the supply of the former, and not expend 
any of it for the latter ; and would in fact make use of 
them for supplying the others with humus. 

We have now considered all that is requisite in a soil, 
in order to furnish its plants with the materials necessary 
for the formation of the woody fibre, the grain, the roots, 
and the stem, and now proceed to the consideration of 
the most important object of agriculture, viz. the pro- 

* When glass contains a very large proportion of potash, it is solu- 
ble in boiling water ; and by combination with other substances, silica 
becomes soluble in water. According to Dr. Jackson, crenic acid en- 
ables water to take it up. 
20* 



234 OF MANURE. 

duction of nitrogen in a form capable of assimilation, — 
the production, therefore, of substances containing this 
element. The leaves, which nourish the woody matter, 
the roots, from which the leaves are formed, and which 
prepare the substances for entering into the composition 
of the fruit, and, in short, every part of the organism of 
a plant, contain azotized matter in very varying propor- 
tions, but the seeds and roots are always particularly rich 
in them. 

Let us now examine in what manner the greatest pos- 
sible production of substances containing nitrogen can 
be effected. Nature, by means of the atmosphere, fur- 
nishes nitrogen to a plant in quantity sufficient for its 
normal growth. Now its growth must be considered as 
normal, when it produces a single seed, capable of re- 
producing the same plant in the following year. Such 
a normal condition would suffice for the existence of 
plants, and prevent their extinction, but they do not ex- 
ist for themselves alone ; the greater number of animals 
depend on the vegetable world for food, and by a wise 
adjustment of nature, plants have the remarkable power 
of converting, to a certain degree, all the nitrogen of- 
fered to them into nutriment for animals. 

We may furnish a plant with carbonic acid, and all 
the materials which it may require, we may supply it 
with humus in the most abundant quantity, but it will not 
attain complete development unless nitrogen is also af- 
forded to it ; an herb will be formed, but no grain, even 
sugar and starch may be produced, but no gluten. 

But when we give a plant nitrogen in considerable 
quantity, we enable it to attract with greater energy, 
from the atmosphere, the carbon which is necessary for 
its nutrition, when that in the soil is not sufficient ; we 



FjECes. urine. 235 

afford to it a means of fixing the carbon of the atmo- 
sphere in its organism. 

We cannot ascribe much of the power of the excre- 
ments of black cattle, sheep, and horses, to the nitrogen 
which they contain, for its quantity is too minute. But 
that contained in the faeces of man is proportionably 
much greater, although by no means constant. In the 
faeces of the inhabitants of towns, for example, who feed 
on animal matter, there is much more of this constituent 
than in those of peasants, or of such people as reside in 
the country. The faeces of those who live principally 
on bread and potatoes are similar in composition and 
properties to those of animals. 

All excrements have in this respect a very variable 
and relative value. Thus, those of black cattle and 
horses, are of great use on soils consisting of lime and 
sand, which contain no silicate of potash and phosphates, 
whilst their value is much less when applied to soils 
formed of argillaceous earth, basalt, granite, porphyry, 
clinkstone, and even mountain limestone, because all 
these contain potash in considerable quantify. In such 
soils human excrements are extremely beneficial, and in- 
crease their fertility in a remarkable degree ; they are, of 
course, as advantageous for other soils also ; but for the 
manure of those first mentioned, the excrements of 
other animals are quite indispensable. 

We possess only one other source of manure which 
acts by its nitrogen, besides the faeces of animals, — 
namely, the urine of man and animals. 

Urine is employed as manure either in the liquid 
state, or with the faeces which are impregnated with 
it. It is the urine contained in them which gives to 
the solid faeces the property of emitting ammonia, a 



236 



OP MANURE. 



property which they themselves possess only in a very 
slight degree. 

When we examine what substances we add to a soil 
by supplying it with urine, we find that this liquid contains 
in solution ammoniacal salts, uric acid, (a substance con- 
taining a large quantity of nitrogen), and salts of phos- 
phoric acid. 

According to Berzdius 1000 parts of human urine 
contain : — 

Urea, 30.10 

Free Lnctic acid*, Lactate of Ammonia, and ani- 
mal matter not separable from them, . . 17.14 



Uric Acid, 

Mucus of the bladder, 
Sulphate of Potash, 
Sulphate of Soda, 
Phosphate of Soda, 
Phosphate of Ammonia, 
Cliloride of Sodium, 
Muriate of Ammonia, 
Phosphates of Magnesia and 
Siliceous earth, . 
Water, . 




1.00 
0.32 
371 
3.16 
2.94 
1.65 
4.45 
1.50 
1.00 
0.03 
933.00 



1000.00 

If we subtract from the above the urea, lactate of am- 
monia, free lactic acid, uric acid, the phosphate and muri- 
ate of ammonia, I per cent, of solid matter remains,, 
consisting of inorganic salts, which must possess the 
same action when brought on a field, whether they are 
dissolved in water or in urine. Hence the powerful 
influence of urine must depend upon its other ingredi- 
ents, namely the urea and ammoniacal salts. The urea 

* Lactic acid has been found in most animal fluids and in several 
plants. It was first obtained from sour milk, hence its name from the 
Latin lac, milk. 



AMMONIA FROM URINE. 237 

in human urine exists partly as lactate of urea, and part- 
ly in a free state. {Henry.) * Now when urine is 
allowed to putrefy spontaneously, that is, to pass into 
that state in which it is used as manure, all the urea in 
combination with lactic acid is converted into lactate of 
ammonia, and that which was free, into volatile carbonate 
of ammonia. 

In dung-reservoirs well constructed and protected 
from evaporation, this carbonate of ammonia is retained 
in the state of solution, and when the putrefied urine is 
spread over the land, a part of the ammonia will escape 
with the water which evaporates, but another portion 
will be absorbed by the soil, if it contains either alumi- 
na or iron ; but in general, only the muriate, phosphate, 
and lactate of ammonia remain in the ground. It is 
these alone, therefore, which enable the soil to exercise 
a direct influence on plants during the progress of their 
growth, and not a particle of them escapes being ab- 
sorbed by the roots. 

On account of the formation of this carbonate of am- 
monia, the urine becomes alkaline, although it is acid in 
its natural state. When it is lost by being volatilized in 
the air, which happens in most cases, the loss suffered 
is nearly equal to one half of the weight of the urine em- 
•ployed, so diat if we fix it, that is, if we deprive it of its 
volatility, we increase its action twofold. The exis- 
tence of carbonate of ammonia in putrefied urine long 
since suggested the manufacture of sal-ammoniac from 
this material. When the latter salt possessed a high 
price, this manufacture was even carried on by the far- 
mer. For this purpose the liquid obtained from dung- 

* Urea consists of nitrogen, hydrogen, carbon, and oxygen. (NH4O 
+ C,NO). 



238 



OF MANURE. 



hills was j)laced in vessels of iron, and subjected to 
distillation ; the product of this distillation was convert- 
ed into muriate of ammonia by the common method. 
(Demachi/.) But it is evident that such a thoughtless 
proceeding must be wholly relinquished, since the nitro- 
gen of 100 lbs. of sal-ammoniac (which contains 26 
parts of nitrogen) is equal to the quantity of nitroge 
contained in 1200 lbs. of the grain of wheat, 1480 lbs. 
of that of barley, or 2755 lbs. of hay. (Boussiugault.) 

The carbonate of ammonia formed by the putrefac- 
tion of urine, can be fixed or deprived of its volatility in 
many ways. 

If a field be strewed with gypsum, and then with pu- 
trefied urine or the drainings of dunghills, all the carbon- 
ate of ammonia will be converted into the sulphate which 
will remain in the soil. 

But there are still simpler means of effecting this 
purpose; — gypsum, chloride of calcium, sulphuric or 
muriatic acid, and super-phosphate of lime, are all sub- 
stances of a very low price, and completely neutralize 
the urine, converting its ammonia into salts which pos- 
sess no volatility. 

If a basin filled with concentrated muriatic acid is 
placed in a common necessary, so that its surface is in 
free communication with the vapors which rise from be-* 
low, it becomes filled after a few days with crystals of 
muriate of ammonia. The ammonia, the presence of 
which the organs of smell amply testify, combines with 
the muriatic acid and loses entirely its volatility, and 
thick clouds or fumes of the salt newly formed hang 
over the basin. In stables the same may be seen. The 
ammonia that escapes in this manner, is not only entire- 
ly lost as far as our vegetation is concerned, but it 



AMMONIA FROM URINE. 239 

works also a slow, though not less certain destruction of 
the walls of the building. For when in contact with the 
lime of the mortar, it is converted into nitric acid, which 
gradually dissolves the lime. The injury thus done to 
a building by the formation of the soluble nitrates has 
received (in Germany) a special name, — salpeierfrass. 

The ammonia emitted from stables and necessaries is 
always in combination with carbonic acid. Carbonate 
of ammonia and sulphate of lime (gypsum) cannot be 
brought together at common temperatures, without mu- 
tual decomposition. The ammonia enters into combi- 
nation with the sulphuric acid, and the carbonic acid 
with the lime, forming compounds which are not vola- 
tile, and, consequently, destitute of all smell. Now if 
we strew the floors of our stables, from time to time, 
with common gypsum, they will lose all their offensive 
smell, and none of the ammonia which forms can be 
lost, but will be retained in a condition serviceable as 
manure. 

With the exception of urea, uric acid contains more 
nitrogen than any other substance generated by the living 
organism ; it is soluble in water, and can be thus absorb- 
ed by the roots of plants, and its nitrogen assimilated in 
the form of ammonia, and of the oxalate, hydrocyanate, 
or carbonate of ammonia. 

It would be extremely interesting to study the trans- 
formations which uric acid suffers in a living plant. For 
the purpose of experiment, the plant should be made to 
grow in charcoal powder previously heated to redness, 
and then mixed with pure uric acid. The examination 
of the juice of the plant, or of the component parts 
of the seed or fruit, would be a means of easily detect- 
ing the differences. 



240 OF MANURE. 

In respect to the quantity of nitrogen contained in 
exciements, 100 parts of the urine of a heahhy man are 
equal to 1300 parts of the fresh dung of a horse, accord- 
ing to the analyses of J\Iacaire and JlJarcet, and to 600 
parts of those of a cow. Hence it is evident that it 
would be of much importance to agriculture if none of 
the human urine were lost. The powerful effects of 
urine as a manure are well known in Flanders, but they 
are considered invaluable by the Chinese, who are the 
oldest agricultural people we know. Indeed so much 
value is attached to the influence of human excrements 
by these people, that laws of the state forbid that any 
of them should be thrown away, and reservoirs are 
placed in every house, in which they are collected with 
the greatest care. No other kind of manure is used for 
their corn-fields. 

China is the birth-place of the experimental art ; the 
incessant striving after experiments has conducted the 
Chinese a thousand years since to discoveries, which 
have been the envy and admiration of Europeans for 
centuries, especially in regard to dyeing and painting, 
and to the manufactures of porcelain, silk, and colors for 
painters. These we were long unable to imitate, and 
yet they were discovered by them without the assistance 
of scientific principles ; for in the books of the Chinese 
we find recipes and directions for use, but never explana- 
tions of processes. 

Half a century sufficed to Europeans, not only to 
equal but to surpass the Chinese in the arts and manufac- 
tures, and this was owing merely to the application of 
correct principles deduced from the study of chemistry. 
But how infinitely inferior is the agriculture of Europe 
10 that of China ! The Chinese are the most admirable 



VALUE OF HUMAN EXCREMENTS. 241 

gardeners and trainers of plants, for each of which they 
understand how to prepare and apply the best adapted 
manure. The agriculture of their country is the most 
perfect in the world ; and there, where the climate in the 
most fertile districts differs little from the European, 
very little value is attached to the excrements of 
animals.* With us, thick books are written, but no 

* This is, however, in consequence of its scarcity. Davis, in his 
History of China, states that every substance convertible into manure 
is diligentlj' husbanded. " The cakes that remain after the expres- 
sion of their vegetable oils, horns and hoofs reduced to powdefj 
tocrether with soot and ashes, and the contents of common sewers are 
much used. The plaster of old kitchens, which in China have na 
chimneys, but an opening at Ihe top, is much valued : so that they 
will sometimes put new plaster on a kitchen for the sake of the old. 
All sorts of hair are used as manure, and barber's shavings are care- 
fully appropriated to that purpose. The annual produce must be con- 
siderable, in a country where some hundred millions of heads are 
kept constantly shaved. Dung of all animals, but more especially- 
night soil, is esteemed above all others. Being sometimes formed 
into cakes, it is dried in the sun, and in this state becomes an object 
of sale to farmers, who dilute it previous to use. They construct 
large cisterns or pits lined with lime plaster, as well as earthern tubs, 
sunk in the ground, with straw over them to prevent evaporation^ 
in which all kinds of vegetables and animal refuse are collected. 
These being diluted with a sufficient quantity of liquid, are left to. 
undergo the putrefactive fermentation, and then applied to the land.'' 

" In the case of every thing except rice, the Chinese seem to ma- 
nure rather the plant itself than the soil, supplying it copiously with, 
their liquid preparation." 

"The Chinese husbandman," observes Sir G. Staunton {Embassy,. 
Vol. II. p. 476,) " always steeps the seeds he intends to sow in liquid 
manure, until they swell, and germination begins to appear, which,, 
experience has taught him, will have the effect of hastening the 
growth of plants, as well as of defending them against the insects 
hidden in the ground in which the seeds are sown. To tlie roots 
of plants and fruit-trees the Chinese farmer applies liquid manure- 
likewise." 

These statements are confirmed by others which have been kindly 

21 



242 OF MANURE. 

experiments inslituted ; the quantity of manure con- 
sumed by this and that plant, is expressed in hundredth 
parts, and yet we know not what manure is ! 

If we admit that the liquid and solid excrements of 
man amount on an average to 1| lbs. daily (| lb. urine 
and I lb. faeces), and that both taken together contain 3 
per cent, of nitrogen, then in one year they will amount 
to 547 lbs., which contain 16.41 lbs. of nitrogen, a 
quantity sufficient to yield the nitrogen of 800 lbs. of 
wheat, rye, oats, or of 900 lbs. of barley. (^Boussin- 
gault.) 

This is much more than it is necessary to add to an 
acre of land, in order to obtain, with the assistance of 
the nitrogen absorbed from the atmosphere, the richest 
possible crop every year. Every town and farm 
might thus supply itself with the manure, which besides 
containing the most nitrogen, contains also the most 
phosphates ; and if an alternation of the crops were 
adopted, they would be most abundant. By using, at 
the same time, bones and the lixiviated ashes of wood, 
the excrements of animals might be completely dis- 
pensed with. 

When human excrements are treated in a proper 
manner, so as to remove the moisture which they con- 
tain without permitting the escape of ammonia, they 
may be put into such a form as will allow them to be 
transported, even to great distances. 

communicated to me by a gentleman whose opportunities for observa- 
tion during a residence in Cliina of several years, were ample, and 
wliose liberality and devotion to agriculture and horticulture have 
already conferred upon the community results of great interest and 
value. — See Appendix. ^ 



VALUE OF HUMAN EXCREMENTS. 243 

This is already attempted In many towns, and the 
preparation of human excrements for transportation con- 
stitutes not an unimportant branch of industry. But the 
manner in which this is done is the most injudicious 
which could be conceived. In Paris, for example, the 
excrements are preserved in the houses in open casks, 
from which they are collected and placed in deep pits 
at Montfaucon, but are not sold until they have attained 
a certain degree of dryness by evaporation in the air. 
But whilst lying in the receptacles appropriated for 
them in the houses, the greatest part of their urea is 
converted into carbonate of ammonia ; lactate and phos- 
phate of ammonia are also formed, and the vegetable 
matters contained in them putrefy ; all their sulphates 
are decomposed, v/hilst their sulphur forms sulphuretted 
hydrogen and hydro-sulphate of ammonia. The mass 
when dried by exposure to the air has lost more than 
half of the nitrogen which the excrements originally 
contained ; for the ammonia escapes into the atmosphere 
along with the water which evaporates ; and the residue 
now consists principally of phosphate of lime, with 
phosphate and lactate of ammonia, and small quantities 
of urate of magnesia and fatty matter. Nevertheless it is 
still a very powerful manure, but its value as such would 
be twice or four times as great, if the excrements be- 
fore being dried were neutralized with a cheap mineral 
acid. 

In other manufactories of manure, the excrements 
whilst still soft are mixed with the ashes of wood, or 
with earth,* both of which substances contain a large 



* This is practised in the vicinity of large cities in the United 
States. 



244 OF MANURE. 

quantity of caustic lime, by means of which a complete 
expulsion of all their ammonia is effected, and they are 
completely deprived of smell. But such a residue 
applied as manure can act only by the phosphates which 
it still contains, for all the ammoniacal salts have been 
decomposed, and their ammonia expelled. 

The sterile soils of the South American coast are 
manured with a substance called guano, consisting of 
urate of ammonia, and other ammoniacal salts, by the 
use of which a luxuriant vegetation and the richest 
crops are obtained. The corn-fields in China receive 
no other manure than human excrements. But we 
cover our fields every year with the seeds of weeds, 
which from their nature and form pass undigested along 
with the excrements through animals, without being de- 
prived of their power of germination, and yet it is con- 
sidered surprising that where they have once flourished, 
they cannot again be expelled by all our endeavours : 
we think it very astonishing, while we really sow them 
ourselves every year. A famous botanist, attached to 
the Dutch embassy to China, could scarcely find a sin- 
gle plant on the corn-fields of the Chinese, except the 
corn itself.* 

The urine of horses contains less nitrogen and phos- 
phates than that of man. According to Fourcroy and 
Vauquelin it contains only five per cent, of solid matter, 
and in that quantity only 0.7 of urea ; whilst 100 parts 
of the urine of man contain more than four times as 
much. 

The urine of a cow is particularly rich in salts of 
potash ; but according to Rouelle and Brande, it is 

* Ingenhouss on the Nutrition of Plants, page 12i) (German edition). 



ITS EFFECT. 245 

almost destitute of salts of soda. The urine of swine 
contains a large quantity of the phosphate of magnesia 
and ammonia ; and hence it is that concretions of this 
salt are so frequently found in the urinary bladders of 
these animals. 

It is evident that if we place the solid or liquid ex- 
crements of man, or the liquid excrements of animals, 
on our land, in equal proportion to the quantity of 
nitrogen removed from it in the form of plants, the 
sum of this element in the soil must increase every 
year ; for the quantity which we thus supply, an- 
other portion is added from the atmosphere. The ni- 
trogen which we export as corn and cattle, and which 
is thus absorbed by large towns, serves only to benefit 
other farms, if we do not replace it. A farm which 
possesses no pastures, and not fields sufficient for the 
cultivation of fodder, requires manure containing nitro- 
gen to be imported from elsewhere, if it is desired to 
produce a full crop. In large farms, the annual expendi- 
ture of nitrogen is completely replaced by means of the 
pastures. 

The only absolute loss of nitrogen, therefore, is lim- 
ited to the quantity which man carries with him to his 
grave ; but this at the utmost cannot amount to more than 
3 lbs. for every individual, and is being collected during 
his whole life. Nor is this quantity lost to plants, for it 
escapes into the atmosphere as ammonia during the pu- 
trefaction and decay of the body. 

A high degree of culture requires an increased supply 
of manure. With the abundance of the manure the pro- 
duce in corn and cattle will augment, but must diminish 
with its deficiency. 

From the preceding remarks it must be evident, that 
21* 



246 OF MANURE. 

the greatest value should be attached to the liquid excre- 
ments of man and animals when a manure is desired 
which shall supply nitrogen to the soil. The greatest 
part of" a superabundant crop, or, in other words, the in- 
crease of growth which is in our power, can be obtained 
exclusively by their means. 

When it is considered that with every pound of am- 
monia which evaporates, a loss of GO lbs. of corn is sus- 
tained, and that with every pound of urine a pound of 
wheat might be produced, the indifference with which 
these liquid excrements are regarded is quite incompre- 
hensible. Ill most places, only the solid excrements im- 
pregnated with the liquid are used, and the dunghills con- 
taining them are protected neither from evaporation nor 
from rain. The solid excrements contain the insoluble, 
the liquid all the soluble phosphates, and the latter con- 
tain likewise all the potash which existed as organic salts 
in the plants consumed by the animals. 

Fresh bones, wool, hair, hoofs, and horn, are manures 
containing nitrogen as well as phosphates, and are conse- 
quently fit to aid the process of vegetable life. 

One hundred parts of dry bones contain from 32 to 
33 per cent, of dry gelatine ; now, supposing this to 
contain the same quantity of nitrogen as animal glue, viz. 
5.28 per cent., then 100 parts of bones must be con- 
sidered as equivalent to 250 parts of human urine. 

Bones may be preserved unchanged for thousands of 
years, in dry or even in moist soils, provided the access 
of rain is prevented, as is exemplified by the bones of 
antediluvian animals found in loam or gypsum, the interior 
parts being protected by the exterior from the action of 
water. But they become warm when reduced to a fine 
powder, and moistened bones generate heat and enter 



CHARCOAL, &C. 247 

into putrefaction ; the gelatine which they contain is de- 
composed, and its nitrogen converted into carbonate of 
ammonia and other ammoniacal sahs, which are retained 
in a great measure by the powder itself. (Bones burnt 
till quite white, and recently heated to redness, absorb 
7.5 times their volume of pure ammoniacal gas.) 

Charcoal in a state of powder must be considered as 
a very powerful means of promoting the growth of plants 
on heavy soils, and particularly on such as consist of ar- 
gillaceous earth. 

Ingenhouss proposed dilute sulphuric acid as a means 
of increasing the fertility of a soil. Now, when this acid 
is sprinkled on calcareous soils, gypsum (sulphate of 
lime) is immediately formed, which of course prevents 
the necessity of manuring the soils with this material. 
100 parts of concentrated sulphuric acid diluted with 
from 800 to 1000 parts of water, are equivalent to 176 
parts of gypsum. 



li*^'' 



PART SECOND. 

OF THE CHEMICAL PROCESSES OF FERMENTATION, 
DECAY, AND PUTREFACTION. 



CHAPTER I. 

CHEMICAL TRANSFORMATIONS. 

Woody fibre, sugar, gum, and all such organic com- 
pounds, suffer certain changes when in contact with other 
bodies, that is, they suffer decomposition. 

There are two distinct modes in which these decom- 
positions take place in organic chemistry. 

When a substance composed of two compound bodies, 
crystallized oxalic acid * for example, is brought in con- 
tact with concentrated sulphuric acid, a complete de- 
composition is effected upon the application of a gentle 
heat. Now crystallized oxalic acid is a combination of 
water with the anhydrous acid f ; but concentrated sul- 
phuric acid possesses a much greater affinity J for water 
than oxalic acid, so that it attracts all the water of crys- 

* An acid found in several plants, particularly of the genera oxalis, 
rumex, &c., combined with potash, and in lichens combined with lime. 
It is composed of carbonic acid and carbonic oxide. 

1 Containing no water. t See Introduction, p. 42, 



250 CHEMICAL TRANSFORMATIONS. 

tallization* from that substance. In consequence of this 
abstraction of the water, anhydrous oxalic acid is set 
free ; but as this acid cannot exist in a free state, a di- 
vision of its constituents necessarily ensues, by which 
carbonic acid and carbonic oxide are produced, and 
evolved in the gaseous form in equal volumes. In this 
example, the decomposition is the consequence of the 
removal of two constituents (the elements of water), 
which unite with the sulphuric acid, and its cause is the 
superior affinity of the acting body (the sulphuric acid) 
for water. In consequence of the removal of the com- 
ponent parts of water, the remaining elements enter into 
a new form ; in place of oxalic acid, we have its ele- 
ments in the form of carbonic acid and carbonic oxide. 

This form of decomposition, in which the change is 
effected by the agency of a body which unites with one 
or more of the constituents of a compound, is quite 
analogous to the decomposition of inorganic substances. 
When we bring sulphuric acid and nitrate of potash (salt- 
petre) together, nitric acid (p. 55, note) is separated in 
consequence of the affinity of sulphuric acid for potash ; 
in consequence, therefore, of the formation of a new 
compound (sulphate of potash). 

In the second form of these decompositions, the 
chemical affinity of the acting body causes the compo- 
nent parts of the body which is decomposed to combine 
so as to form new compounds, of which either both, or 
only one, combine with the acting body. Let us take 
dry wood, for example, and moisten it with sulphuric 
acid ; after a short time the wood is carbonized, while 
the sulphuric acid remains unchanged, with the exception 

* See Introduction, p. 113. 



i 



EXAMPLES. 251 

of its being united with more water than it possessed 
before. Now this water did not exist as such in the 
wood, although its elements, oxygen and hydrogen, were 
present ; but by the chemical attraction of sulphuric acid 
for water, they were in a certain measure compelled to 
unite in this form ; and in consequence of this, the car- 
bon of wood was separated as charcoal. 

Hydrocyanic acid,* and water, in contact with hydro- 
chloric acid,f are mutually decomposed. The nitrogen 
of the hydrocyanic acid, and a certain quantity of the 
hydrogen of the water, unite together and form ammo- 
nia ; whilst the carbon and hydrogen of the hydrocyanic 
acid combine with the oxygen of the water, and form 
formic acid.\. The ammonia combines with the muriatic 
acid. Here the contact of muriatic acid with water and 
hydrocyanic acid causes a disturbance in the attraction of 
the elements of both compounds, in consequence of 
whicli they arrange themselves into new combinations, 
one of which, — ammonia, — possesses the power of 
uniting with the acting body. 

Inorganic chemistry can present instances analogous to 
this class of decomposition also ; but there are forms of 
organic chemical decomposition of a very different kind, 
in which none of the component parts of the matter 
which suffers decomposition enters into combination with 
the body which determines the decomposition. In cases 
of this kind a disturbance is produced in the mutual at- 
traction of the elements of a compound, and they in con- 
sequence arrange themselves into one or several new 

* See p. 110. 

t Formerly called Muriatic Acid, obtained from sea salt and com- 
posed of Hydrogen and Chlorine. 
t See page 127, note. 



252 CHEMICAL TRANSFORMATIONS. 

combinations, which are incapable of suffering further 
change under the same conditions. 

When, by means of the chemical affinity of a second 
body, by the influence of heat, or through any other 
causes, the composition of an organic compound is made 
to undergo such a change, that its elements form two or 
more new compounds, this manner of decomposition is 
called a chemical transformation or metamorphosis. It 
is an essential character of chemical transformations, 
that none of the elements of the body decomposed are 
singly set at liberty. 

The changes which are designated by the terms fer- 
mentation, decay, and putrefaction, are chemical transfor- 
mations effected by an agency which has hitherto escaped 
attention, but the existence of which will be proved in 
the following pages. 



CHAPTER II. 

ON THE CAUSES WHICH EFFECT FERMENTATION, 
DECAY,* AND PUTREFACTION. 

Attention has been recently directed to the fact, 
that a body in the act of combination or decomposition 



* An essential distinction is drawn in the following part of the work, 
between decay and ■putrefaction {Verwesitng und Faulniss), and they 
are shown to depend on different causes ; but as the word decay is 
not generally applied to a distinct species of decomposition, and does 
not indicate its true nature, I shall in future^ at the suggestion of the 
author, employ the term ercmacausis, the meaning of which has been 
already explained. — Trans. 



I 



THEIR CAUSE. 253 

exercises an influence upon any other body with which 
it may be in contact. Platinum, for example, does not 
decompose nitric acid ; it may be boiled with this acid 
without being oxidized by it, even when in a state of 
such fine division that it no longer reflects light (black 
spongy platinum). But an alloy of silver and platinum 
dissolves with great ease in nitric acid ; the oxidation 
which the silver sufi^ers, causes the platinum to submit 
to the same change ; or, in other words, the latter body 
from its contact with the oxidizing silver, acquires the 
property of decomposing nitric acid. 

Copper does not decompose water, even when boiled 
in dilute sulphuric acid, but an alloy of copper, zinc, 
and nickel, dissolves easily in this acid with evolution 
of hydrogen gas. 

Tin decomposes nitric acid with great facility, but 
water with difficulty : and yet, when tin is dissolved in 
nitric acid, hydrogen is evolved at the same time, from 
a decomposition of the water contained in the acid, and 
ammonia is formed in addition to oxide of tin. 

In the examples here given, the only combination or 
decomposition which can be explained by chemical 
affinity is the last. In the other cases, electrical action 
ought to have retarded or prevented the oxidation of the 
platinum or copper while they were in contact with sil- 
ver or zinc, but as experience shows, the influence of 
the opposite electrical conditions is m.ore than counter- 
balanced by chemical actions. 

The same phenomena are seen in a less dubious form 
in compounds, the elements of which are held together 
only by a weak affinity. It is well known that tfiere 
are chemical compounds of so unstable a nature, that 
changes in temperature and electrical condition, or even 
22 



254 CHEMICAL TRANSFORMATIONS. 

simple mechanical friction, or contact with bodies of 
apparently totally indifferent natures, cause such a dis- 
turbance in the attraction of their constituents, that the 
latter enter into new forms, without any one of them 
combining with the acting body. These compounds 
appear to stand but just within the limits of chemical 
combination, and agents exercise a powerful influence 
on them, which are completely devoid of action on 
compounds of a stronger affinity. Thus, by a slight in- 
crease of temperature, the elements of hypochlorous 
acid separate from one another with evolution of heat 
and light ; chloride of nitrogen explodes by contact with 
many bodies, which combine neither with chlorine nor 
nitrogen at common temperatures ; and the contact of 
any solid substance is sufficient to cause the explosion 
of iodide of nitrogen, or fulminating silver. 

It has never been supposed that the causes of the de- 
composition of these bodies should be ascribed to a 
peculiar power, difi'erent from that which regulates 
chemical affinity, — a power which mere contact with 
the down of a feather is sufficient to set in activity, and 
which, once In action, gives rise to the decomposition. 
These substances have always been viewed as chemical 
combinations of a very unstable nature, in which the 
component parts are in a state of such tension, that 
the least disturbance overcomes their chemical affinity. 
They exist only by the vis incrtice, and any shock or 
movement is sufficient to destroy the attraction of (heir 
component parts, and consequently their existence in 
their definite form. 

Peroxide of hydrogen * belongs to this class of 

* A remarkable compound consislhig ol' 1 Hydrogen, and 2 Oxy- 
gen. See description and process for obtaining in Webster's Chem- 
istry, p. 134. 



THEIR CAUSE. 255 

bodies ; it is decomposed by all substances capable of 
attracting oxygen from it, and even by contact with 
many bodies, such as platinum or silver, which do not 
enter into combination with any of its constituents. In 
this respect, its decomposition depends evidently upon 
the same causes which effect that of idoide of nitrogen, 
or fulminating silver. Yet it is singular that the cause 
of the sudden separation of the component parts of per- 
oxide of hydrogen has been viewed as different from 
those of common decomposition, and has been ascribed 
to a new power termed the catalytic force.* Now, it 
has not been considered, that the presence of the plati- 
num and silver serves here only to accelerate the de- 
composition ; for without the contact of these metals, 
the peroxide of hydrogen decomposes spontaneously, 
although very slowly. The sudden separation of the 
constituents of peroxide of hydrogen differs from the 
decomposition of gaseous hypochlorous acid, or solid 
iodide of nitrogen, only in so far as the decomposition 
takes place in a liquid. 

A remarkable action of peroxide of hydrogen has at- 
tracted much attention, because it differs from ordinary 
chemical phenomena. This is the reduction which 
certain oxides suffer by contact with this substance, on 
the instant at which the oxygen separates from the 
water. The oxides thus easily reduced,! are those of 
which the whole, or part at least, of their oxygen is re- 
tained merely by a feeble affinity, such as the oxides of 
silver and of gold, and peroxide of lead. 

Now, other oxides which are very stable in composi- 

* See Introduction, p. 215. 

t When the oxygen is separated from a metallic oxide and the 
metal obtained, it is said to be reduced and the process is termed 
reduction. 



256 CHEMICAL TRANSFORMATIONS. 

lion, effect the decomposition of peroxide of hydrogen, 
without experiencing the smallest change ; but when 
oxide of silver is employed to effect the decomposition, 
all the oxygen of the silver is carried away with that 
evolved from the peroxide of hydrogen, and as a result 
of the decomposition, water and metallic silver remain. 
When peroxide * of lead is used for the same purpose, 
half its oxygen escapes as a gas. Peroxide of manga- 
nese may in the same manner be reduced to the protox- 
ide, and oxygen set at liberty, if an acid is at the same 
time present, which will exercise an affinity for the pro- 
toxide and convert it into a soluble salt. 

A similar phenomenon occurs, when carbonate of sil- 
ver is treated with several organic acids. 

Now no other explanation of these phenomena can be 
given, than that a body in the act of combination or 
decomposition enables another body, with which it is in 
contact, to enter into the same state. It is evident that 
the active slate of the atoms of one body has an influence 
upon the atoms of a body in contact with it ; and if these 
atoms are capable of the same change as the former, 
they likewise undergo that change ; and combinations 
and decompositions are the consequence. But when 
the atoms of the second body are not capable of such an 
action, any further disposition to change ceases from the 
moment at which the atoms of the first body assume the 
state of rest, that is, when the changes or transformations 
of this body are quite completed. 

This influence exerted by one compound upon the 
other, is exactly similar to that which a body in the act 

* A peroxide is one that, contains the largest proportion of oxygen. 
When several compounds of metals and oxygen occur, that which 
contains the smallest proportion of oxygen is called the first or pro- 
toxide. 



THEIR CAUSE. 257 

of combustion exercises upon a combustible body in its 
vicinity ; with this difference only, that the causes which 
determine the participation and duration of these con- 
ditions are different. For the cause, in the case of the 
combustible body, is heat, which is generated every 
moment anew ; whilst in the phenomena of decomposi- 
tion and combination, which we are considering at pres- 
ent, the cause is a body in the state of chemical action, 
which exerts the decomposing influence only so long as 
this action continues. 

Numerous facts show that motion alone exercises a 
considerable influence on chemical forces. Thus, the 
power of cohesion does not act in many saline solutions, 
even when they are fully saturated with salts, if ihey are 
permitted to cool whilst at rest. In such a case, the 
salt dissolved in a liquid does not crystallize, but when 
a grain of sand is thrown into the solution, or when it 
receives the slightest movement, the whole liquid be- 
comes suddenly solid while heat is evolved. The same 
phenomenon happens with water, for this liquid may be 
cooled much under 82° (0° C), if kept completely 
undisturbed, but solidifies in a moment when put in 
motion. 

The atoms of a body must in fact be set in motion 
before they can overcome the vis inertice so as to arrange 
themselves into certain forms. Motion, by overcoming 
the vis inertice^ gives rise immediately to another arrange- 
ment of the atoms of a body, that is, to the production 
of a compound which did not before exist in it. Of 
course these atoms must previously possess the power 
of arranging themselves in a certain order, otherwise 
both friction and motion would be without the smallest 
influence. 

22* 



258 CHEMICAL TRANSFORMATIONS. 

The simple permanence in position of the atoms of a 
body, is the reason that so many compounds appear to 
present themselves, in conditions, and with properties, 
different from those which they possess, when they obey 
the natural attractions of their atoms. Thus sugar and 
glass, when melted and cooled rapidly, are transparent, 
of a conchoidal fracture, and elastic and flexible to a 
certain degree. But the former becomes dull and opake 
on keeping, and exhibits crystalline faces by cleavage, 
which belong to crystallized sugar. Glass assumes also 
the same condition, when kept soft by heat for a long 
period ; it becomes white, opake, and so hard as to 
strike fire with steel. Now, in both these bodies, the 
compound molecules evidently have different positions 
in the two forms. In the first form their attraction did 
not act in the direction in which their power of cohesion 
was strongest. It is known also, that when sulphur is 
melted and cooled rapidly by throwing it into cold water, 
it remains transparent, elastic, and so soft that it may be 
drawn out into long threads; but that after a few hours 
or days, it becomes again hard and crystalline. 

The remarkable fact here is, that the amorphous sugar 
or sulphur returns again into the crystalline condition, 
without any assistance from an exterior cause ; a fact 
which shows that their molecules have assumed another 
position, and that they possess, therefore, a certain de- 
gree of mobility, even in the condition of a solid. A 
very rapid transposition or transformation of this kind is 
seen in arragonite, a mineral which possesses exactly the 
same composition as calcareous spar, but of which the 
hardness and different crystalline form prove that its 
molecules are arranged in a different manner. When a 
-crystal of arragonite is heated, an interior motion of its 



FEEMENTATION AND PUTREFACTION. 259 

molecules is caused by the expansion ; the permanence 
of their arrangement is destroyed ; and the crystal splin- 
ters with much violence, and falls into a heap of small 
crystals of calcareous spar. 

It is impossible for us to be deceived regarding the 
causes of these changes. They are owing to a dis- 
turbance of the state of equilibrium, in consequence of 
which, the particles of the body put in motion obey other 
afKnities or their own natural attractions. 

But if it is true, as we have just shown it to be, that 
mechanical motion is sufficient to cause a change of con- 
dition in many bodies, it cannot be doubted that a body 
in the act of combination or decomposition is capable 
of imparting the same condition of motion or activity 
in which its atoms are to certain other bodies : or in 
other words, to enable other bodies with which it is 
in contact to enter into combinations, or suffer decom- 
positions. 

The reality of this influence has been already suffi- 
ciently proved by the facts derived from inorganic chem- 
istry, but it is of much more frequent occurrence in the 
relations of organic matters, and causes very striking and 
vironderful phenomena. 

By the terms fermentation, putrefaction, and erema- 
causis, are meant those changes in form and properties 
which compound organic substances undergo when sep- 
arated from the organism, and exposed to the influence 
of water and a certain temperature. Fermentation and 
putrefaction are examples of that kind of decomposition 
which we have named transformations ; the elements of 
the bodies capable of undergoing these changes arrange 
themselves into new combinations, in which the con- 
stituents of water generally take a part. 



260 CHEMICAL TRANSFORMATIONS 

Ercmacausis (or decay) differs from fermentation and 
putrefaction, inasmuch as it cannot take place without 
the access of air, the oxygen of which is absorbed by 
the decaying bodies. Hence it is a process of slow 
combustion, in which heat is uniformly evolved, and 
occasionally even light. In the processes of decompo- 
sition, termed fermentation and putrefaction, gaseous 
products are very frequently formed, which are either 
inodorous, or possess a very offensive smell. 

The transformations of those matters which evolve 
gaseous products widiout odor, are now, by pretty 
general consent, designated by the term fermentation ; 
whilst to the spontaneous decomposition of bodies which 
emit gases of a disagreeable smell, the term putrefaction 
is applied. But the smell is of course no distinctive 
character of the nature of the decomposition, for both 
fermentation and putrefaction are processes of decompo- 
sition of a similar kind, the one of substances destitute 
of nitrogen, the other of substances which contain it. 

It has also been customary to distinguish from fermen- 
tation and putrefaction a particular class of transforma- 
tions, viz., those in which conversions and transpositions 
are effected without the evolution of gaseous products. 
But the conditions under which the products of the 
decomposition present themselves are purely accidental ; 
there is therefore no reason for the distinction just 
mentioned. 



OF ORGANIC COMPOUNDS. 261 

CHAPTER III. 

FERMENTATION AND PUTREFACTION. 

Several bodies appear to enter spontaneously into the 
states of fermentation and putrefaction, particularly such 
as contain nitrogen or azotized substances. Now, it is 
very remarkable, that very small quantities of these sub- 
stances, in a state of fermentation- or putrefaction, possess 
the power of causing unlimited quantities of similar mat- 
ters to pass into the same state. Thus, a small quantity 
of the juice of grapes in the act of fermentation, added 
to a large quantity of the same fluid, which does not 
ferment, induces the state of fermentation in the whole 
mass. So likewise the most minute portion of milk, 
paste, juice of the beet-root, flesh, or blood, in the state 
of putrefaction, causes fresh milk, paste, juice of the 
beet-root, flesh, or blood, to pass into the same condi- 
tion when in contact with them. 

These changes evidently differ from the class of com- 
mon decompositions which are effected by chemical af- 
finity ; they are chemical actions, conversions, or de- 
compositions, excited by contact with bodies already in 
the same condition. In order to form a clear idea of 
these processes, analogous and less complicated phe- 
nomena must previously be studied. 

The compound nature of the molecules of an organic 
body, and the phenomena presented by them when in 
relation with other matters, point out the true cause of 
these transformations. Evidence is afforded even by 
simple bodies, that in the formation of combinations, the 
force with which the combining elements adhere to one 



262 CHEMICAL TRANSFORMATIONS 

another is inversely proportional to the number of simple 
atoms in the compound molecule. 

There are many facts which prove, that the most 
simple inorganic compounds are also the most stable, 
and undergo decomposition with the greatest difficulty, 
whilst those which are of a complex composition yield 
easily to changes and decompositions. The cause of 
this evidently is, that in proportion to the number of 
atoms which enter into a compound, the directions in 
which their attractions act will be more numerous. 

Whatever ideas we may entertain regarding matter in 
general, the existence of chemical proportions removes 
every doubt respecting the presence of certain limited 
groups or masses of matter which we have not the power 
of dividing. The particles of matter called equivalents 
in chemistry are not infinitely small, for they possess a 
weight, and are capable of arranging themselves in the 
most various ways, and of thus forming innumerable com- 
pound atoms. The properties of these compound atoms 
differ in organic nature, not only according to the form, 
but also in many instances according to the direction and 
place, which the simple atoms take in the compound 
molecules. 

When we compare the composition of organic com- 
pounds with inorganic, we are quite amazed at the ex- 
istence of combinations, in one single molecule of which, 
ninety or several hundred atoms or equivalents are united. 
Thus, the compound atom of an organic acid of very 
simple composition, acetic acid for example, contains 
twelve equivalents of simple elements ; one atom of 
kinovic acid contains 33, 1 of sugar 36, 1 of amygdalin 
90, and 1 of stearic acid 138 equivalents. The compo- 
nent parts of animal bodies are infinitely more complex 
even than these. 



OP ORGANIC COMPOUNDS. 263 

Inorganic compounds differ from organic in as great a 
degree in their other characters as in their simplicity of 
constitution. Thus, the decomposition of a compound 
atom of sulphate of potash is aided by numerous causes, 
such as the power of cohesion, or the capability of its 
constituents to form solid, insoluble, or at certain tem- 
peratures volatile compounds with the body brought into 
contact with it, and nevertheless a vast number of other 
substances produce in it not the slightest change. Now, 
in the decomposition of a complex organic atom, there is 
nothing similar to this. 

The empirical formula of sulphate of potash is SKO4.* 
It contains only 1 eq. of sulphur, and 1 eq. of potassium. 
We may suppose the oxygen to be differently distributed 
in the compound, and by a decomposition we may re- 
move a part or all of it, or replace one of the constitu- 
ents of ihe compound by another substance. But we 
cannot produce a different arrangement of the atoms, 
because they are already disposed in the simplest form in 
which it is possible for them to combine. Now, let us 
compare the composition of sugar of grapes with the 
above : here 12 eq. of carbon, 12 eq. of hydrogen, and 
12 eq. of oxygen, are united together, and we know 
that they are capable of combining with each other in 
the most various ways. From the formula of sugar, we 
might consider it either as a hydrate of carbon, wood, 
starch, or sugar of milk, or further, as a compound of 
either with alcohol or of formic acid with sachulmin. f 
Indeed we may calculate almost all the known organic 

* S denotes sulphur, K (Kali) potash, O oxygen, 4 the nun)ber of 
atoms. When no number is used, one atom is understood. 

I The black precipitate obtained by the action of hydrochloric acid 
on sugar. 



264 CHEMICAL TRANSFORMATIONS 

compounds containing no nitrogen from sugar, by simply- 
adding the elements of water, or by replacing any one of 
its elementary constituents by a different substance. The 
elements necessary to form these compounds are there- 
fore contained in the sugar, and they must also possess 
the power of forming numerous combinations amongst 
themselves by their mutual attractions. 

Now, when we examine what changes sugar undergoes 
when brought into contact with other bodies which exer- 
cise a marked influence upon it, we find, that these 
changes are not confined to any narrow Hmits, like those 
of inorganic bodies, but are in fact unlimited. 

The elements of sugar yield to every attraction, and 
to each in a peculiar manner. In inorganic compounds, 
an acid acts upon a particular constituent of the body, 
which it decomposes, by virtue of its affinity for that 
constituent, and never resigns its proper chemical char- 
acter, in whatever form it may be applied. But when it 
acts upon sugar, and induces great changes in it, it does 
this, not by its superior affinity for a base existing in the 
sugar, but by disturbing the equilibrium in the mutual 
attraction of the elements of the sugar amongst them- 
selves. Muriatic and sulphuric acids, which differ so 
much from one another both in characters and composi- 
tion, act in the same manner upon sugar. But the action 
of both varies according to the state in which they are ; 
thus they act in one way when dilute, in another when 
concentrated, and even difi^erences in their temperature 
cause a change in their action. Thus sulphuric acid of 
a moderate degree of concentration converts sugar into 
a black carbonaceous matter, forming at the same time 
acetic and formic acids. But when the acid is more 
diluted, the sugar is converted into two brown substances, 



OF ORGANIC COMPOUNDS. 265 

both of ihem containing carbon and the elements of 
water. Again, when sugar is subjected to the action of 
alkahes, a whole series of different new products are ob- 
tained, while oxidizing agents, such as nitric acid, pro- 
duce from it carbonic acid, acetic acid, oxalic acid, 
formic acid, and many other products which have not 
yet been examined. 

If from the facts here stated we estimate the power 
with which the elements of sugar are united together, 
and judge of the force of their attraction by the resist- 
ance which they offer to the action of bodies brought 
into contact with them, we must regard the atom of sugar 
as belonging to that class of compound atoms, which ex- 
ist only by the vis inertice. of their elements. Its ele- 
ments seem merely to retain passively the position and 
condition in which they had been placed, for we do not 
observe that they resist a change of this condition by 
their own mutual attraction, as is the case with sulphate 
of potash. 

Now it is only such combinations as sugar, combina- 
tions therefore which possess a very complex molecule, 
which are capable of undergoing the decompositions 
named fermentation and putrefaction. 

We have seen that metals acquire a power which they 
do not of themselves possess, namely, that of decom- 
posing water and nitric acid, by simple contact with other 
metals in the act of chemical combination. We have 
also seen, that peroxide of hydrogen and the persulphuret 
of the same element, in the act of decomposition, cause 
other compounds of a similar kind, but of which the 
elements are much more strongly combined, to undergo 
the same decomposition, although they exert no chemical 
affinity or attraction for them or their constituents. The 
23 



266 CHEMICAL TRANSFORMATIONS 

cause which produces these phenomena will be also re- 
cognised, by attentive observation, in those matters which 
excite fermentation or putrefaction. All bodies in the 
act of combination or decomposition have the property 
of inducing those processes ; or, in other words, of caus- 
ing a disturbance of the statical equilibrium in the attrac- 
tions of the elements of complex organic molecules, in 
consequence of which those elements group themselves 
anew, according to their special affinities. 

The proofs of the existence of this cause of action 
can be easily produced ; they are found in the characters 
of the bodies which effect fermentation and putrefaction, 
and in the regularity with which the distribution of the 
elements takes place in the subsequent transformations. 
This regularity depends exclusively on the unequal affini- 
ty which they possess for each other in an isolated con- 
dition. The action of water on wood, charcoal, and 
cyanogen, the simplest of the compounds of nitrogen, 
suffices to illustrate the whole of the transformations of 
organic bodies ; of those in which nitrogen is a constitu- 
ent, and of those in which it is absent. 



CHAPTER IV. 



ON THE TRANSFORMATION OF BODIES WHICH DO 
NOT CONTAIN NITROGEN AS A CONSTITUENT, AND 
OF THOSE IN WHICH IT IS PRESENT. 

When oxygen and hydrogen, combined in equal equiv- 
alents, as in steam, are conducted over charcoal, heated 
to the temperature at which it possesses the power to 



OF BODIES DESTITUTE OF NITROGEN. 267 

enter into combination with one of these elements, a 
decomposition of the steam ensues. An oxide of car- 
bon (either carbonic oxide or carbonic acid) is under all 
circumstances formed, while the hydrogen of the water 
is liberated, or, if the temperature be sufficient, unites 
with the carbon forming carburetted hydrogen. Accord- 
ingly, the carbon is shared between the elements of the 
water, the oxygen and hydrogen. Now a participation 
of this kind, but even more complete, is observed in 
every transformation, whatever be the nature of the 
causes by which it is effected. 

Acetic and meconic* acids suffer a true transforma- 
tion under the influence of heat, that is, their component 
elements are disunited, and form new compounds without 
any of them being singly disengaged. 

In these cases the carbon of the bodies decomposed 
is shared between the oxygen and hydrogen ; part of it 
unites with the oxygen and forms carbonic acid, whilst 
the other portion enters into combination with the hydro- 
gen, and an oxide of a carbohydrogen is formed, in which 
all the hydrogen is contained. 

In a similar manner, when alcohol is exposed to a 
gentle red heat, its carbon is shared between the elements 
of the water, — an oxide of a carbohydrogen which con- 
tains all the oxygen, and some gaseous compounds of 
carbon and hydrogen being produced. 

It is evident that during transformations caused by heat, 
no foreign affinities can be in play, so that the new com- 
pounds must result merely from the elements arranging 
themselves, according to the degree of their mutual affini- 
ties, into new combinations which are constant and un- 

* An acid existing in opium, and named from the Greek for poppy. 



268 CHEMICAL TRANSFORMATIONS 

changeable in the conditions under which they were origi- 
nally formed, but undergo changes when these conditions 
become different. If we compare the products of two 
bodies, similar in composition but different in properties, 
which are subjected to transformations by two different 
causes, we find that the manner in which the atoms are 
transposed, is absolutely the same in both. 

In the transformation of wood in marshy soils, by what 
we call putrefaction, its carbon is shared between the 
oxygen and hydrogen of its own substance, and of the 
water, — carburetted hydrogen is consequently evolved, 
as well as carbonic acid, both of which compounds have 
an analogous composition (CH2, C02).* 

Thus also in that transformation of sugar, which is 
called fermentation, its elements are divided into two 
portions ; the one, carbonic acid, which contains f of the 
oxygen of sugar ; and the other, alcohol, which contains 
all its hydrogen. 

In the transformation of acetic acid produced by a red 
heat, carbonic acid which contains | of the oxygen of 
the acetic acid is formed, and acetone which contains all 
its hydrogen. 

It is evident from these facts, that the elements of a 
complex compound are left to their special attractions 
whenever their equilibrium is disturbed, from whatever 
cause this disturbance may proceed. It appears also, 
that the subsequent distribution of the elements, so as to 
form new combinations, always takes place in the same 
way, with this difference only, that the nature of the 
products formed is dependent upon the number of atoms 
of the elements which enter into action ; or in oiher 

* C carbon, H hydrogen, O oxygen. 



OF BODIES CONTAINING NITROGEN. 269 

words, that the products differ ad infinitum^ according 
to the composition of the original substance. 

Transformation of Bodies containing Nitrogen. 

When those substances are examined which are most 
prone to fermentation and putrefaction, it is found that 
they are all, without exception, bodies which contain 
nitrogen. In many of these compounds, a transposition 
of their elements occurs spontaneously as soon as they 
cease to form part of a living organism ; that is, when 
they are drawn out of the sphere of attraction in which 
alone they are able to exist. 

There are, indeed, bodies destitute of nitrogen, which 
possess a certain degree of stability only when in com- 
bination, but which are unknown in an isolated condi- 
tion, because their elements, freed from the power by 
which they were held together, arrange themselves ac- 
cording to their own natural attractions. 

The case is very different with azotized bodies. It 
would appear that there is some peculiarity in the nature 
of nitrogen, which gives its compounds the power to 
decompose spontaneously with so much facility. Now, 
nitrogen is known to be the most indifferent of all the 
elements ; it evinces no particular attraction to any one 
of the simple bodies, and this character it preserves in 
all its combinations, a character which explains the 
cause of its easy separation from the matters vi^ith which 
it is united. 

It is only when the quantity of nitrogen exceeds a 
certain limit, that azotized compounds have some degree 
of permanence. Their liability to change is also dimin- 
ished, when the quantity of nitrogen is very small in pro- 
23* 



270 CHEMICAL TRANSFORMATIONS 

portion to that of the other elements with which it is 
united, so that their mutual attractions preponderate. 

This easy transposition of atoms is best seen in the 
fulminating silvers, in fulminating mercury, in the iodide 
or chloride of nitrogen, and in all fulminating com- 
pounds. 

All other azotized substances acquire the same power 
of decomposition, when the elements of water are 
brought into play, and indeed, the greater part of them 
are not capable of transformation, while this necessary 
condition to the transposition of their atoms is absent. 
Even the compounds of nitrogen, which are most liable 
to change, such as those which are found in animal bod- 
ies, do not enter into a state of putrefaction when dry. 

The result of the known transformations of azotized 
substances proves, that the water does not merely act as 
a medium in which motion is permitted to the elements 
in the act of transposition, but that its influence depends 
on chemical affinity. When the decomposition of such 
substances is effected with the assistance of water, their 
nitrogen is invariably liberated in the form of ammonia. 
This is a fixed rule without any exceptions, whatever may 
be the cause which produces the decompositions. All 
organic compounds containing nitrogen, evolve the whole 
of that element in the form of ammonia when acted upon 
by alkalies. Acids, and increase of temperature, pro- 
duce the same effect. It is only when there is a defi- 
ciency of water or its elements, that cyanogen or other 
azotized compounds are produced. 

From these facts it may be concluded, that ammonia 
is the most stable compound of nitrogen ; and that hy- 
drogen and nitrogen possess a degree of affinity for each 



OF BODIES CONTAINING NITROGEN. 271 

Other, which surpasses the attraction of the latter body 
for any other element. 

Already in considering the transformations of sub- 
stances containing no nitrogen, we have seen that a 
powerful cause effecting the disunion of the elements of 
a complex organic atom in a definite manner, is the 
great affinity which carbon possesses for oxygen. But 
carbon is also invariably contained in azotized com- 
pounds, while the great affinity of nitrogen for hydrogen 
furnishes a new and powerful cause, facilitating the 
transposition of their component parts. Thus, in the 
bodies which do not contain nitrogen we have one ele- 
ment, and in those in which that substance is present, 
two elements, which mutually share the elements of 
water. Hence there are two opposite affinities at play, 
which strengthen mutually each other's action. 

Now we know, that the most powerful attractions 
may be overcome by the influence of two affinities. 
Thus, a decomposition of alumina may be effected with 
the greatest facility, when the affinity of charcoal for 
oxygen, and of chlorine for aluminum, are both put in 
action, although neither of these alone has any influence 
upon it. There is in the nature and constitution of the 
compounds of nitrogen a kind of tension of their com- 
ponent parts, and a strong disposition to yield to trans- 
formations, which effect spontaneously the transposition 
of their atoms on the instant that water or its elements 
are brought in contact with them. 

The characters of the hydrated cyanic acid, one of 
the simplest of all the compounds of nitrogen, are per- 
haps the best adapted to convey a distinct idea of the 
manner in which the atoms are disposed of in transfor- 
mations. This acid contains nitrogen, hydrogen, and 



272 CHEMICAL TRANSF*0RMAtiON9 

Oxygen, in such proportions, that the addition of a cer- 
tain quantity of the elements of water is exactly suffi- 
cient to cause the oxygen contained in the water and 
acid to unite with the carbon and form carbonic acid, 
and the hydrogen of the water to combine with the 
nitrogen and form ammonia. The most favorable con- 
ditions for a complete transformation are, therefore, 
associated in these bodies, and it is well known, that 
the disunion takes place on the instant that the cyanic 
acid and water are brought into contact, the mixture 
being converted into carbonic acid and ammonia, with 
brisk effervescence. 

This decomposition may be considered as the type 
of the transformations of all azotized compounds ; it is 
putrefaction in its simplest and most perfect form, be- 
cause the new products, the carbonic acid and ammonia, 
are incapable of further transformations. 

Putrefaction assumes a totally different and much 
more complicated form, when the products, which are 
first formed, undergo a further change. In these cases 
the process consists of several stages, of which it is 
impossible to determine when one ceases and the other 
begins. 

The transformations of cyanogen, a body composed 
of carbon and nitrogen, and the simplest of all the com- 
pounds of nitrogen, will convey a clear idea of the great 
variety of products which are produced in such a case : 
it is the only example of the putrefaction of an azotized 
body which has been at all accurately studied. 

A solution of cyanogen in water becomes turbid after 
a short time, and deposits a black, or broivnish black 
matter^ which is a combination of ammonia with another 
body, produced by the simple union of cyanogen with 



OF BODIES CONTAINING NITROGEN. 273 

water. This substance is insoluble in water, and is thus 
enabled to resist further change. 

A second transformation is effected by the cyanogen 
being shared between the elements of the water, in con- 
sequence of which cyanic acid is formed by a certain 
quantity of the cyanogen combining with the oxygen of 
the water, while hydrocyanic acid is also formed by 
another portion of the cyanogen uniting with the hydro- 
gen which was liberated. 

Cyanogen experiences a third transformation, by 
which a complete disunion of its elements takes place, 
these being divided between the constituents of the 
water. Oxalic acid is the one product of this disunion, 
and ammonia the other. 

Cyanic acid, the formation of which has been men- 
tioned above, cannot exist in contact with water, being 
decomposed immediately into carbonic acid and ammo- 
nia. The cyanic acid, however, newly formed in the 
decomposition of cyanogen, escapes this decomposition 
by entering into combination with the free ammonia, by 
which urea * is produced. 

The hydrocyanic acid is also decomposed into a 
brown matter which contains hydrogen and cyanogen, 
the latter in greater proportion than it does in the gas- 
eous state. Oxalic acid, urea, and carbonic acid, are 
also formed by its decomposition, and formic acid and 
ammonia are produced by the decomposition of its 
radical. 

Thus, a substance into the composition of which only 
two elements (carbon and nitrogen) enter, yields eight 
totally different products. Several of these products 

* See page 237, note. 



274 CHEMICAL TRANSFORMATIONS. 

are formed by the transformation of the original body, 
its elements being shared between the constituents of 
water ; others are produced in consequence of a further 
disunion of those first formed. The urea and carbonate 
of ammonia are generated by the combination of two 
of the products, and in their formation the whole of the 
elements have assisted. 

These examples show, that the results of decompo- 
sition by fermentation or putrefaction comprehend very 
different phenomena. The first kind of transformation 
is, the transposition of the elements of one complex 
compound, by which new compounds are produced 
with or without the assistance of the elements of water. 
In the products newly formed in this manner, either the 
same proportions of those component parts which were 
contained in the matter before transformation, are found, 
or with them, an excess, consisting of the constituents 
of water which had assisted in promoting the disunion 
of the elements. 

The second kind of transformation consists of the 
transpositions of the atoms of two or more complex 
compounds, by which the elements of both arrange 
themselves mutually into new products, with or without 
the cooperation of the elements of water. In this kind 
of transformations, the new products contain the sum of 
the constituents of all the compounds which had taken 
a part in the decomposition. 

The first of these two modes of decomposition is 
that designated fermentation^ the second putrefaction ; 
and when these terms are used in the following pages, 
it will always be to distinguish the two processes above 
described, which are so different in their results. 



FERMENTATION OF SUGAR. 275 



CHAPTER V. 



FERMENTATION OF SUGAR. 



The peculiar decomposition which sugar suffers may 
be viewed as a type of all the transformations desig- 
nated fermentation.* 

Thiinard obtained from 100 grammes f of cane-sugar 
0.5262 of absolute alcohol. 100 parts of sugar from 
the cane yield 103.89 parts of carbonic acid and alco- 
hol. The entire carbon in these products is equal to 
42 parts, which is exactly the quantity originally con- 
tained in the sugar. 

The analysis of sugar from the cane, proves that it 
contains the elements of carbonic acid and alcohol, 
minus 1 atom of water. The alcohol and carbonic acid 
produced by the fermentation of a certain quantity of 
sugar, contain together one equivalent of oxygen, and 
one equivalent of hydrogen, the elements, therefore, of 
one equivalent of water, more than the sugar con- 
tained. The excess of weight in the products is owing 
to the elements of water having taken part in the meta- 
morphosis of the sugar. 

It is known that I atom of sugar contains 12 equiva- 
lents of carbon, both from the proportions in which it 
unites with bases, and from the composition of sac- 
charic acid the product of its oxidation. Now none of 
these atoms of carbon are contained in the sugar as car- 
bonic acid, because the whole quantity is obtained as 
oxalic acid, when sugar is treated with hypermanganate 

* See illustration in Appendix. 

t The gramme equals 15-4440 grains. 



276 FERMENTATION OF SUGAR. 

of potash (^Gregory) ; and as oxalic acid is a lower 
degree of the oxidation of carbon than carbonic acid, it 
is impossible to conceive that the lower degree should 
be produced from the higher, by means of one of the 
most powerful agents of oxidation which we possess. 

It can be also proved, that the hydrogen of the sugar 
does not exist in it in the form of alcohol, for it is con- 
verted into water and a kind of carbonaceous matter, 
when treated with acids, particularly with such as con- 
tain no oxygen ; and this manner of decomposition is 
never suffered by a compound of alcohol. 

Sugar contains, therefore, neither alcohol nor car- 
bonic acid, so that these bodies must be produced by 
a different arrangement of its atoms, and by their union 
with the elements of water. 

In the metamorphosis of the sugar (by the aid of 
yeast), the elements of the yeast, by contact with which 
its fermentation was effected, take no appreciable part in 
the transposition of the elements of the sugar ; for in 
the products resulting from the action, we find no com- 
ponent part of this substance. 

We may now study the fermentation of a vegetable 
juice, which contains not only saccharine matter, but 
also such substances as albumen and gluten. The juices 
of parsnips, beet-roots, and onions, are well adapted for 
this purpose. When such a juice is mixed with yeast 
at comnioa temperatures, it ferments like a solution of 
sugar. Carbonic acid gas escapes from it with effer- 
vescence, and in the liquid, alcohol is found in quantity 
exactly corresponding to that of the sugar originally 
contained in the juice. But such a juice undergoes 
spontaneous decomposition at a temperature of from 
95° to 104° (35° — 40°C.). Gases possessing an 



YEAST, OR FERMENT. 277 

offensive smell are evolved in considerable quantity, 
and when the liquor is examined after the decomposi- 
tion is completed, no alcohol can be detected. The 
sugar has also disappeared, and with it all the azotized 
compounds which existed in the juice previously to its 
fermentation. Both were decomposed at the same 
time ; the nitrogen of the azotized compounds remains 
in the liquid as ammonia, and, in addition to it, there 
are three new products, formed from the component 
parts of the juice. One of these is lactic acid, the 
slightly volatile compound found in the animal organ- 
ism ; the other is the crystalline body which forms the 
principal constituent of manna ; and the third is a mass 
resembling gum-arabic, which forms a thick viscous 
solution with water. These three products weigh more 
than the sugar contained in the juice, even without cal- 
culating the weight of the gaseous products. Hence 
they are not produced from the elements of the sugar 
alone. None of these three substances could be de- 
tected in the juice before fermentation. They must, 
therefore, have been formed by the interchange of the 
elements of the sugar with those of the foreign sub- 
stances also present. It is this mixed transformation of 
two or more compounds which receives the special name 
of futref action. 

Yeast., or Ferment. When attention is directed to the 
condition of those substances which possess the power 
of inducing fermentation and putrefaction in other bod- 
ies, evidences are found in their general characters, 
and in the manner in which they combine, that they all 
are bodies, the atoms of which are in the act of transpo- 
sition. 

The characters of the remarkable matter which is de- 
24 



278 YEAST, OR FERMENT. 

posited in an insoluble state during the fermentation of 
beer, wine, and vegetable juices, may be first studied. 

This substance, which has been called yeast or fer- 
ment^ from the power which it possesses of causing fer- 
mentation in sugar, or saccharine vegetable juices, pos- 
sesses all the characters of a compound of nitrogen in 
the state of putrefaction and ertmacausis. 

Like wood in the state of eremacausis, yeast converts 
the oxygen of the surrounding air into carbonic acid, 
but it also evolves this gas from its own mass, like bod- 
ies in the state of putrefaction (Colin). When kept 
under water, it emits carbonic acid, accompanied by 
gases of an offensive smell (Theiiard), and is at last con- 
verted into a substance resembling old cheese (Proust). 
But when its own putrefaction is completed, it has no 
longer the power of inducing fermentation in other bod- 
ies. The presence of water is quite necessary for sus- 
taining the properties of ferment, for by simple pressure 
its power to excite fermentation is much diminished, 
and is completely destroyed by drying. Its action is 
arrested also by the temperature of boiling water, by al- 
cohol, common salt, an excess of sugar, oxide of mer- 
cury, corrosive sublimate, pyroligneous acid, sulphurous 
acid, nitrate of silver, volatile oils, and in short by all 
antiseptic substances. 

The insoluble part of the substance called ferment 
does not cause fermentation. For when the yeast from 
wine or beer is carefully washed with water, care being 
taken that it is always covered with this fluid, the resi- 
due does not producefe rmentation. 

The soluble part of ferment likewise does not excite 
fermentation. An aqueous infusion of ysast may be 
mixed with a solution of sugar, and preserved in vessels 



ITS PROPERTIES. 279 

from which the air is excluded, without either experi- 
encing the slightest change. What then, we may ask, 
is the matter in ferment which excites fermentation, if 
neither the soluble nor insoluble parts possess the pow- 
er ? This question has been answered by Colin in the 
most satisfactory manner. He has shown that in reality 
it is the soluble part. But before it obtains this power, 
the decanted infusion must be allowed to cool in contact 
with the air, and to remain some time exposed to its ac- 
tion. When introduced into a solution of sugar in this 
state, it produces a brisk fermentation ; but without 
previous exposure to the air, it manifests no such prop- 
erty. 

The infusion absorbs oxygen during its exposure to 
the air, and carbonic acid may be found in it after a short 
time. 

Yeast produces fermentation in consequence of the 
progressive decomposition which it suffers from the ac- 
tion of air and water. 

Now, when yeast is made to act on sugar, it is found, 
that after the transformation of the latter substance 
into carbonic acid and alcohol is completed, part of the 
yeast itself has disappeared. 

From 20 parts of fresh yeast from beer, and 100 parts 
of sugar, Thenard obtained, after the fermentation was 
completed, 13.7 parts of an insoluble residue, which di- 
minished to 10 parts when employed in the same way 
with a fresh portion of sugar. These ten parts were 
white, possessed of the properties of woody fibre, and 
had no further action on sugar. 

It is evident, therefore, that during the fermentation 
of sugar by yeast, both of these substances suffer decom- 
position at the same time, and disappear in consequence. 



2S0 YEAST, OR FEKMENT. 

But if yeast be a body which excites fermentation by 
being itself in a state of decomposition, all other matters 
in the same condition should have a similar action upon 
sugar ; and this is in reality the case. Muscle, urine, 
isinglass, osmazome,* albumen, cheese, gliadine, gluten, 
legumin, and blood, when in a state of putrefaction, 
have all the power of producing the putrefaction, or fer- 
mentation of a solution of sugar. Yeast, which by con- 
tinued washing, has entirely lost the property of inducing 
fermentation, regains it when its putrefaction has recom- 
menced, in consequence of its being kept in a warm sit- 
uation for some time. 

Yeast and putrefying animal and vegetable matters act 
as peroxide of hydrogen does on oxide of silver, when 
they, induce bodies with which they are in contact to en- 
ter into the same state of decomposition. The dis- 
turbance in the attraction of the constituents of the 
peroxide of hydrogen effects a disturbance in the attrac- 
tions of the elements of the oxide of silver, the one 
being decomposed, on account of the decomposition of 
the other. 

Now if we consider the process of the fermentation 
of pure sugar, in a j)ractical point of view, we meet with 
two facts of constant occurrence. When the quantity 
of ferment is too small in proportion to that of the sugar, 
its putrefaction will be completed before the transforma- 
tion of all the sugar is effected. Some sugar here re- 
mains undecomposed, because the cause of its transfor- 
mation is absent, viz. contact with a body in a state of 
decomposition. 

* An extractive animal matter on which the peculiar flavor of broth 
is supposed to depend, hence its name, from the Greek for odor and 
broth. 



ITS MODE OF ACTION. 281 

But when the quantity of ferment predonninates, a 
certain quantity of it remains after all the sugar has fer- 
mented, its decomposition proceeding very slowly, on 
account of its insolubility in water. This residue of 
ferment is still able to induce fermentation, when intro- 
duced into a fresh solution of sugar, and retains the same 
power until it has passed through all the stages of its 
own transformation. 

Hence a certain quantity of yeast is necessary in 
order to effect the transformation of a certain portion of 
sugar, not because it acts by its quantity increasing any 
affinity, but because its influence depends solely on its 
presence, and its presence is necessary, until the last 
atom of sugar is decomposed. 

These facts and observations point out the existence 
of a new cause, which effects combinations and decom- 
positions. This cause is the action which bodies in a 
state of combination or decomposition exercise upon 
substances, the component parts of which are united to- 
gether by a feeble affinity. In its action it resembles a 
peculiar power, attached to a body in the state of com- 
bination or decomposition, but exerting its influence be- 
yond the sphere of its own attractions. 

We are now able to account satisfactorily for many 
known phenomena. 

A large quantity of hippuric * acid may be obtained 
from the fresh urine of a horse, by the addition of mu- 
riatic acid ; but when the urine has undergone putrefac- 
tion, no trace of it can be discovered. The urine of 
man contains a considerable quantity of urea, but when 
the urine putrefies, the urea entirely disappears. When 

* See Note, p. 138. 
24 * 



2S2 YEAST, OR FERMENT. 

urea is added to a solution of sugar in the state of fer- 
mentation, it is deconriposed into carbonic acid and 
ammonia. No asparagin * can be detected in a putrefied 
infusion of asparagin, liquorice-root, or tlie root o( althcea 
officinalis ( Marshmallovv) . 

It has already been mentioned, that the strong affinity 
of nitrogen for hydrogen, and that of carbon for oxygen, 
is the cause of the facility with which the elements 
of azotized compounds are disunited ; those affinities 
aiding each other, inasmuch as by virtue of them dif- 
ferent elements of the compound strive to take posses- 
sion of the different elements of water. Now since it 
is found that no body destitute of nitrogen possesses, 
when pure, the property of decomposing spontaneously 
whilst in contact with water, we must ascribe this prop- 
erty which azotized bodies possess in so eminent a de- 
gree, to something peculiar in the nature of the com- 
pounds of nitrogen, and to their constituting, in a certain 
measure, more highly organized atoms. 

Every azotized constituent of ihe animal or vegetable 
organism enters spontaneously into putrefaction, when 
exposed to moisture and a high temperature. 

Azotized matters are accordingly the only causes of 
fermentation and putrefaction in vegetable substances. 

Putrefaction, on account of its effects, as a mixed 
transformation of many different substances, may be 
classed with the most powerful processes of deoxidation, 
by which the strongest affinities are overcome. 

When a solution of gypsum in water is mixed with a 
decoction of sawdust, or any other organic matter capa- 

* A peculiar principle obtained from asparagus. See Brande's 
Chemistry, p. 1042. 



NATURE OF FERMENTATION. 283 

ble of putrefaction, and preserved in well-closed vessels, 
it is found, after some time, that the solution contains no 
more sulphuric acid, but in its place carbonic and free 
hydrosulphuric acid, (sulphuretted hydrogen,) betvi^een 
which the lime of the gypsum is shared. In stagnant 
water containing sulphates in solution, crystallized py- 
rites (sulphuret of iron) is observed to form on the de- 
caying roots. 

Now we know that in the putrefaction of wood under 
water, when air therefore is excluded, a part of its car- 
bon combines with the oxygen of the water, as well as 
with the oxygen which the wood itself contains ; whilst 
its hydrogen and that of the decomposed water are 
liberated either in a pure state, or as carburetted hydro- 
gen. The products of this decomposition are therefore 
of the same kind as those generated when steam is con- 
ducted over red-hot charcoal. 

It is evident, that if with the water a substance contain- 
ing a large quantity of oxygen, such as sulphuric acid, 
be also present, the matters in the state of putrefaction 
will make use of the oxygen of that substance as well as 
that of the water, in order to form carbonic acid ; and 
the sulphur and hydrogen being set free will combine 
whilst in the nascent state, producing hydrosulphuric 
acid, which will be again decomposed if metallic oxides 
be present ; and the results of this second decomposi- 
tion will be water and metallic sulphurets. 

The putrefied leaves of looad (^Isatis tinctoria), in 
contact with indigo-blue, water, and alkalies, suffer 
further decomposition, and the indigo is deoxidized and 
dissolved. 

During the putrefaction of gluten, carbonic acid, and 
pure hydrogen gas are evolved ; phosphate, acetate, 



284 YEAST, OR FERMENT. 

caseate, and lactate of ammonia being at the same time 
produced in such quantity, that the further decomposi- 
tion of the gluten ceases. But when the supply of water 
is renewed, the decomposition begins again, and in addi- 
tion to the salts just mentioned, carbonate of ammonia 
and a white crystalline matter resembling mica (caseous 
oxide) are formed, together with hydrosulphate of am- 
monia, and a mucilaginous substance coagulable by chlo- 
rine. Lactic acid is almost always produced by the 
putrefaction of organic bodies. 

We may now compare fermentation and putrefaction 
with the decomposition which organic compounds suffer 
under the influence of a high temperature. Dry distil- 
lation would appear to be a process of combustion or 
oxidation going on in the interior of a substance, in 
which a part of the carbon unites with all or part of the 
oxygen of the compound, while other new compounds 
containing a large proportion of hydrogen are necessarily 
produced. Fermentation may be considered as a process 
of combustion or oxidation of a similar kind, taking place 
in a liquid between the elements of the same matter, at a 
very slightly elevated temperature ; and putrefaction as a 
process of oxidation, in which the oxygen of all the 
substances present comes into play. 



i 



DECAY. CONDITIONS FOR ITS OCCURRENCE. 285 

CHAPTER VI. 

EREMACAUSIS, OR DECAY. 

In organic nature, besides the processes of decompo- 
sition named fermentation and putrefaction, another and 
not less striking class of changes occurs, which bodies 
suffer from the influence of the air. This is the act of 
gradual combination of the combustible elements of a 
body with the oxygen of the air ; a slow combustion or 
oxidation, to which we shall apply the term of erema- 
causis.* 

The conversion of wood into humus, the formation 
of acetic acid out of alcohol, nitrification,! and numerous 
other processes, are of this nature. Vegetable juices 
of every kind, parts of animal and vegetable substances, 
moist sawdust, blood, &c., cannot be exposed to the air, 
without suffering immediately a progressive change of 
color and properties, during which oxygen is absorbed, 
these changes do not take place when water is excluded, 
or when the substances are exposed to the temperature 
of 32°, and it has been observed that different bodies 
require different degrees of heat. In order to effect the ab- 
sorption of oxygen, and, consequently, their eremacausis. 
The property of suffering this change is possessed in the 
highest degree by substances which contain nitrogen. 

The conditions which determine the commencement 
of eremacausis are of various kinds. Many organic sub- 
stances, particularly such as are mixtures of several more 
simple matters, oxidize in the air when simply moistened 

* See page 95. t Formation of nitre, 



286 EREMACAUSIS, OR DECAY. 

with water ; others not until they are subjected to the 
action of alkahes ; but the greatest part of them undergo 
this state of slow combustion or oxidation, when brought 
in contact with other decaying matters.^ 

The eremacausis of an organic matter is retarded 
or completely arrested by all those substances which 
prevent fermentation or putrefaction. Mineral acids, 
salts of mercury, aromatic substances, empyreumatic 
oils, and oil of turpentine, possess a similar action in this 
respect. The latter substances have the same effect 
on decaying bodies as on phosphuretted hydrogen, the 
spontaneous inflammability of which they destroy. 

Many bodies which do not decay when moistened 
with water, enter into eremacausis when in contact with 
an alkali. Gallic acid, haematin,* and many other com- 
pounds, may be dissolved in water and yet remain un- 
altered, but if the smallest quantity of a free alkali is 
present, they acquire the property of attracting oxygen, 
and are converted into a brown substance like humus, 
evolving very frequently at the same time carbonic acid. 
(Chevreul.) 

A very remarkable kind of eremacausis takes place 
in many vegetable substances, when they are exposed 
to the influence of air, water, and ammonia. They 
absorb oxygen very rapidly, and form splendid violet or 
red-colored liquids, as in the case of orcin and erythrin.f 
They now contain an azotized substance, not in the form 
of ammonia. 

All these facts show that the action of oxygen seldom 
affects the carbon of decaying substances, and this cor- 
responds exactly to what happens in combustion at high 

* The colorinop matter of loorwood. 1 Coloring matters in archil. 



NATURE OF THE PROCESS. 287 

temperatures. It is well known, for example, that when 
no more oxygen is admitted to a compound of carbon 
and hydrogen than is sufficient to combine with its hydro- 
gen, the carbon is not burned, but is separated as lamp- 
black;* while, if the quantity of oxygen is not suffi- 
cient even to consume all the hydrogen, new compounds 
are formed, such as naphthalin f and similar matters, 
which contain a smaller proportion of hydrogen than 
those compounds of carbon and hydrogen which pre- 
viously existed in the combustible substance. 

There is no example of carbon combining directly 
with oxygen at common temperatures, but numerous facts 
show that the hydrogen, in certain states of condensation, 
possess that property. Lamp-black which has been 
heated to redness may be kept in contact with oxygen 
gas, without forming carbonic acid ; but lamp-black, 
impregnated with oils which contain a large proportion 
of hydrogen, gradually becomes warm, and inflames 
spontaneously. The spontaneous inflammability of the 
charcoal used in the fabrication of gunpowder has been 
correctly ascribed to the hydrogen which it contains in 
considerable quantity ; for during its reduction to powder, 
no trace of carbonic acid can be detected in the air sur- 
rounding it ; it is not formed until the temperature of the 
mass has reached the red heat. The heat which pro- 
duces the inflammation is therefore not caused by the 
oxidation of the carbon. 

The substances which undergo eremacausis may be 
divided into two classes. The first class comprehends 
those substances which unite with the oxygen of the air, 

* As in the combustion of spirits of turpentine, now much em- 
ployed under various names, in lamps, 
t A substance obtained from coal tar. 



288 EREMACAUSIS, OR DECAY. 

without evolving carbonic acid ; and the second, such 
as emit carbonic acid by absorbing oxygen. 

When the oil of bitter almonds is exposed to the air, 
it absorbs two equivalents of oxygen, and is converted 
into benzoic acid ; but half of the oxygen absorbed com- 
bines with the hydrogen of the oil, and forms water, 
which remains in union with the anhydrous benzoic 
acid.* 

But, although it appears very probable that the oxygen 
acts primarily and principally upon hydrogen, the most 
combustible constituent of organic matter in the state 
of decay ; still it cannot thence be concluded that the 
carbon is quite devoid of the power to unite with oxy- 
gen, when every particle of it is surrounded with hydro- 
gen, an element with which the oxygen combines with 
greater facility. 

We know, on the contrary, that nitrogen, which can- 
not be made to combine with oxygen directly, is oxid- 
ized and forms nitric acid, when mixed with a large 

* According to the experiments of Dobereiner, 100 parts of pyro- 
gallic acid absorb 38.09 parts of oxygen when in contact with ammo- 
nia and water ; the acid being changed in consequence of this absorp- 
tion into a mouldy substance, whicli contains less oxygen than the 
acid itself. It is evident that the substance which is formed is not 
a higher oxide; and it is found, on comparing the quantity of the 
oxygen absorbed with that of tiie hydrogen contained in the acid, that 
they are exactly in the proportions for forming water. 

When colorless orcin is exposed together with ammonia to the 
contact of oxj'gen gas, the beautiful red-colored orcein is produced. 
Now, the only changes which take place here are, that the absorption 
of oxygen by the elements of orcin and ammonia causes the formation 
of water ; I equivalent of orcin Cl8 H12 08, and 1 equivalent of 
ammonia, NH3 absorb .5 equivalents of oxygen, and 5 equivalents of 
water are produced, the composition of orcein being C18 HIO 08 N. 
(Dumas.) In this case it rs evident, that the oxygen absorbed has 
united merely with the hydrogen. — L. 



NATURE OF THE PROCESS. 289 

quantity of hydrogen, and burned in oxygen gas. In this 
case its affinity is evidently increased by the combustion 
of the hydrogen, which is in fact connmunicated to it. 
It is conceivable, that, in a similar manner, the carbon 
may be directly oxidized in several cases, obtaining from 
its contact with hydrogen in eremacausis a property 
which it does not itself possess at common temperatures. 
But the formation of carbonic acid during the eremacau- 
sis of bodies which contain hydrogen, must in most cases 
be ascribed to another cause. It appears to be formed 
in a manner similar to the formation of acetic acid, by 
the eremacausis of saliculite of potash.* 

An alkaline solution of haematin being exposed to an 
atmosphere of oxygen, 0.2 Grm. absorb 23.6 cubic cen- 
timeters of oxygen gas in twenty-four hours, the alkali 
acquiring at the same time 6 cubic centimeters of car- 
bonic acid. (Clievreul.) But these 6 cubic centime- 
ters of carbonic acid contain only an equal volume of 
oxygen, so that it is certain from this experiment that f^ 
of the oxygen absorbed have not united with the carbon. 
It is highly probable, that during the oxidation of the' 
hydrogen, a portion of the carbon had united with the- 
oxygen contained in the haematin, and had separated from 
the other elements as carbonic acid. 

The experiments of De Saussure upon the decay of 
woody fibre, show that such a separation is quite possi- 
ble. Moist woody fibre evolved one volume of carbonic 
acid for every volume of oxygen which it absorbed. It 
has just been mentioned that carbonic acid contains its 

" This salt, when exposed to a moist atniospliere, absorbs 3 atoms of 
oxygen ; mcJanic acid is produced, a bodj' resembling humus, in con- 
sequence of the formation of which, the elements of 1 atom of acetic 
acid are separated from the saliculous acid. — L. See Appendix. 
25 



290 EREMACAUSIS, OR DECAY. 

own volume of oxygen. Now, woody fibre contains 
carbon and the elements of water, so that the result of 
the action of oxygen upon it is exactly the same as if 
pure charcoal had combined directly with oxygen. But 
the characters of woody fibre show, that the elements of 
water are not contained in it in the form of water ; for, 
were this the case, starch, sugar, and gum must also be 
considered as hydrates of carbon. 

But if the hydrogen does not exist in woody fibre in 
the form of water, the direct oxidation of the carbon 
cannot be considered as at all probable, without reject- 
ing all the facts established by experiment regarding the 
process of combustion at low temperatures. 

If we examine the action of oxygen upon such a sub- 
stance as alcohol, which contains a large quantity of hy- 
drogen, we find most distinctly, that the direct formation 
of carbonic acid is the last stage of its oxidation, and that 
it is preceded by a series of changes, the last of which 
is a complete combustion of the hydrogen.* 

The absorption of oxygen by drying oils certainly 
does not depend upon the oxidation of their carbor> ; for 
in raw nut-oil, for example, which was not free from 
mucilage and other substances, only twenty-one volumes 

* Aldehyde, acetic acid, formic acid, oxalic acid, and carbonic acid, 
form a connected chain of products arising from the oxidation of alco- 
hol ; and the successive changes which this fluid experiences from the 
action of oxj'gen may be readily traced in them. Aldehyde is alcohol 
viinus hydrogen ; acetic acid is formed by the direct union of alde- 
hyde with oxygen. Formic acid and water are formed by the union 
of acetic acid with oxygen. When all the hydrogen is removed from 
this formic acid, oxalic acid is produced ; and the latter acid is con- 
verted into carbonic acid by uniting with an additional portion of oxy- 
gen. All these products appear to be formed simultaneously, by the 
action of oxidizing agents on alcohol; but it can scarcely be doubted, 
that the formation of the last ])rodnct,the carbonic acid, does not take 
place until all the hydrogen has been abstracted. — L. 



NATURE OF THE PROCESS. 291 

of carbonic acid were formed for every 146 volumes of 
oxygen gas absorbed. 

It must be remembered, that combustion or oxidation 
at low temperatures produces results quite similar to 
combustion at high temperatures with limited access of 
air. The most combustible element of a compound, 
which is exposed to the action of oxygen, must become 
oxidized first, for its superior combustibility is caused by 
its being enabled to unite with oxygen at a temperature 
at which the other elements cannot enter into that combi- 
nation ; this property having the same effect as a greater 
affinity. 

The combustibility of potassium is no measure of its 
affinity for oxygen ; we have reason to believe that the 
attraction of magnesium and aluminium for oxygen is 
greater than that of potassium for the same element ; but 
neither of those metals oxidizes either in air or water 
at common temperatures, whilst potassium decomposes 
water with great violence, and appropriates its oxygen. 

Phosphorus and hydrogen combine with oxygen at 
ordinary temperatures, the first in moist air, the second, 
when in contact with finely-divided platinum ; while 
charcoal requires a red heat before it can enter into 'Com- 
bination with oxygen. It is evident that phosphorus and 
hydrogen are more combustible than charcoal, that is, 
that their affinity for oxygen at common temperatures is 
greater ; and this is not the less certain, because it is 
found, that carbon in certain other conditions shows a 
much greater affinity for oxygen than either of those sub- 
stances. 

In putrefaction, the conditions are evidently present, 
under which the affinity of carbon for oxygen comes into 
play ; neither expansion, cohesion, nor the gaseous state 



292 EREMACAUSIS, OR DECAT, 

opposes it, whilst in eretnacausis all these restraints have 
to be overcome. 

The evolution of carbonic acid during the decay or 
eremacausis of animal or vegetable bodies, which are rich 
in hydrogen, must accordingly be ascribed to a transpo- 
sition of the elements or disturbance in their attractions, 
similar to that which gives rise to the formation of car- 
bonic acid in the processes of fermentation and putre- 
faction. 

The eremacausis of such substances is, therefore, a 
decomposition analogous to the putrefaction of azotized 
bodies. For in these there are two affinities at play ; 
the affinity of nitrogen for hydrogen, and that of carbon 
for oxygen, which facilitate the disunion of the elements. 
Now there are two affinities also in action in those bodies 
which decay with the evolution of carbonic acid. One 
of these affinities is the attraction of the oxygen of the 
air for the hydrogen of the substance, which corresponds 
to the attraction of nitrogen for the same element ; and 
the other is the affinity of the carbon of the substance for 
its oxygen, which is constant under all circumstances. 

When wood putrefies in marshes, carbon and oxygen 
are separated from its elements in the form of carbonic 
acid, and hydrogen in the form of carburetted hydrogen. 
But when wood decays or putrefies in tlie air, its hydro- 
gen does not combine with carbon, but with oxygen, for 
which it has a much greater affinity at common tem- 
peratures. 

Now it is evident from the complete similarity of these 
processes, that decaying and putrefying bodies can mu- 
tually replace one another in their reciprocal actions. 

All putrefying bodies pass into the state of decay 
when exposed freely to the air ; and all decaying matters 



OF BODIES DESTITUTE OF NITROGEN. 293 

into that of putrefaciion, when air is excluded. All 
bodies, likewise, in a state of decay are capable of indu- 
cing putrefaction in other bodies in the same manner as 
putrefying bodies themselves do. 



CHAPTER VII. 

EREMACAUSIS, OR DECAY, OF BODIES WHICH DO NOT 
CONTAIN NITROGEN : FORMATION OF ACETIC ACID. 

All those substances which appear to possess the 
property of entering spontaneously into fermentation and 
putrefaction, do not in reality suffer those changes with- 
out some previous disturbance in the attraction of their 
elements. Eremacausis always precedes fermentation 
and putrefaction, and it is not until after the absorption of 
a certain quantity of oxygen that the signs of a transfor- 
mation in the interior of the substances show themselves. 

It is a very general error to suppose that organic sub- 
stances have the power of undergoing change spontane- 
ously, ivithout the aid of an external cause. When they 
are not in a state of change, it is necessary, before they 
can assume that state, that the existing equilibrium of 
their elements should be disturbed ; and the most common 
cause of this disturbance is undoubtedly the atmosphere 
which surrounds all bodies. 

The juices of the fruit or other part of a plant which 
very readily undergo decomj)osition, retain their proper- 
ties unchanged as long as they are protected from imme- 
diate contact with the air, that is, as long as the cells or 
organs in which they are contained resist the influence of 
25* 



294 EREMACAUSIS, OR DECAY, 

the air. It is not iiniil after tlie juices have been exposed 
to the air, and have absorbed a certain quantity of oxygen, 
that the substances dissolved in them begin to be decom- 
posed. 

The beautiful experiments of Gay-Lussac upon the 
fermentation of the juice of grapes, as well as the im- 
portant practical improvements to which they have led, 
are the best proofs of the atmosphere having an influence 
upon the changes of organic substances. The juice of 
grapes which were expressed under a receiver filled with 
mercury, so that air was completely excluded, did not 
ferment. But when the smallest portion of air was in- 
troduced, a certain quantity of oxygen became absorbed, 
and fermentation immediately began. When the juice 
was expressed from the grapes in contact with air, under 
the conditions therefore necessary to cause its fermenta- 
tion, still this change did not ensue when the juice was 
heated in close vessels to the temperature of boiling 
water. When thus treated, it could be preserved for 
years without losing its property of fermenting. A fresh 
exposure to the air at any period caused it to ferment. 

Animal food of every kind, and even the most delicate 
vegetables, may be preserved unchanged if healed to the 
temperature of boiling water in vessels from which the 
air is completely excluded. Food thus prepared has 
been kept for fifteen years, and upon opening the vessels 
after this long time, has been found as fresh and well- 
flavored as when originally placed in them.* 

* The process is as follows ; Let the substance to be preserved be 
first parboiled, or rather somewhat more, the bones of the meat being 
previously removed. Put the meat into a tin cylinder, fill up the 
vessel with seasoned rich soup, and then solder on the lid, pierced 
with a small hole. When this has been done, let the tin vessel thus 



OF BODIES DESTITUTE OF NITROGEN. 295 

The action of the oxygen in these processes of de- 
composition is very simple ; it excites changes in the 
composition of the azoiized matters dissolved in the 
juices; — the mode of combination of the elements of 
those matters undergoes a disturbance and change in con- 
sequence of their contact with oxygen. The oxygen 
acts here in a similar manner to the friction or motion 
which effects the mutual decomposition of two salts, the 
crystallization of salts from their solution, or the explo- 
sion of fulminating mercury. It causes the state of rest 
to be converted into a state of motion. 

When this condition of intestine motion is once ex- 
cited, the presence of oxygen is no longer necessary. 
The smallest particle of an azotized body in this act of 
decomposition exercises an influence upon the particles 
in contact with it, and the state of motion is thus propa- 
gated through the substance. The air may now be com- 
pletely excluded, but the fermentation or putrefaction 
proceeds uninterruptedly to its completion. It has been 
remarked that the mere contact of carbonic acid is suffi- 



prepared be placed in brine and heated to the boiling point, to com- 
plete the cooking of the meat. The hole of the lid is now to be 
closed by soldering, whilst the air is rarefied. The vessel is then al- 
lowed to cool, and from the diminution of volume, in consequence of 
the reduction of temperature, both ends of the cylinder are pressed 
inwards and become concave. The tin cases, thus hermetically 
sealed, are exposed in a test-chamber, for at least a month, to a tem- 
perature above what they are ever likely to encounter; from 90° to 
110° F. If the process has failed, putrefaction takes place, and o-as 
is evolved, which will cause the ends of the case to bulge, so as to 
render them convex, instead of concave. But the contents of those 
cases which stand the test will infallibly keep perfectly sweet and 
good in any climate, and for any number of years. If there be any 
taint about the meat when put up, it inevitably ferments, and is de- 
tected in the proving process.— Ure's Diet, of Jlrts and Manuf. 



296 EREMACAUSIS, OR DECAY, 

cient to produce fermentation in the juices of several 
fruits. 

Tlie contact of ammonia and alkalies in general may 
be mentioned amongst the chemical conditions which de- 
termine the commencement of eremacausis ; for their 
presence causes many substances to absorb oxygen and 
to decay, in which neither oxygen nor alkalies alone pro- 
duce that change. 

Thus alcohol does not combine with the oxygen of 
the air at common temperatures. But a solution of pot- 
ash in alcohol absorbs oxygen with much rapidity, and 
acquires a brown color. The alcohol is found after a 
short time to contain acetic acid, formic acid, and the 
products of the decomposition of aldehyde by alkalies, 
including aldehyde resin, which gives the liquid a brown 
color. 

The most general condition for the production of ere- 
macausis in organic matter is contact with a body already 
in the state of eremacausis or putrefaction. We have 
here an instance of true contagion ; for the communica- 
tion of the state of combustion is in reality the effect of 
the contact. 

It is decaying wood which causes fresh wood around 
it to assume the same condition, and it is the very finely 
divided woody fibre in the act of decay, which in moist- 
ened gall-nuts converts the tannic acid with such rapidity 
into gallic acid. 

A most remarkable and decided example of this in- 
duction of combustion has been observed by De Saussure. 
It has already been mentioned, that moist woody fibre, 
cotton, silk, or vegetable mould, in the act of fermenta- 
tion or putrefaction, converts oxygen gas which may sur- 
round it into carbonic acid, without change of volume. 



OF BODIES DESTITUTE OF NITROGEN, 297 

Now, De Saussure added a certain quantity of hydrogen 
gas to the oxygen, and observed a dinriinution in volume 
immediately after the addition. A part of the hydrogen 
gas had disappeared, and along with it a portion of the 
oxygen, but a corresponding quantity of carbonic acid 
gas had not been formed. The hydrogen and oxygen 
had disappeared in exactly the same proportion as that in 
which they combine to form water ; a true combustion 
of the hydrogen, therefore, had been induced by mere 
contact with matter in the slate of eremacausis. The 
action of the decaying substance here produced results 
exactly similar to those effected by spongy platinum ; 
but that they proceeded from a different cause was shown 
by the fact, that the presence of carbonic oxide, which 
arrests completely the action of platinum on carburetted 
hydrogen, did not retard in the slightest degree the 
combustion of the hydrogen in contact with the decaying 
bodies. 

But the same bodies were found by De Saussure not 
to possess the property just described, before they were 
in a state of fermentation or decay ; and he has shown 
that even when they are in this state, the presence of an- 
tiseptic matter destroys completely all their influence. 

Let us suppose a volatile substance containing a large 
quantity of hydrogen, to be substituted for the hydrogen 
gas in De Saussure's experiments. Now, the hydrogen 
in such compounds being contained in a state of greater 
condensation would suffer a more rapid oxidation, that is, 
its combustion would be sooner completed. This prin- 
ciple is in reality attended to in the manufactories in 
which acetic acid is prepared according to the new plan. 
In the process there adopted all the conditions are afford- 
ed for the eremacausis of alcohol, and for its consequent 
conversion into acetic acid. 



298 EREMACAUSIS, OR DECAY, 

The alcohol is exposed to a moderate heat, and spread 
over a very extended surface, but these conditions are 
not sufficient to effect its oxidation. The alcohol must 
be mixed with a substance which is with facility changed 
by the oxygen of the air, and either enters into erema- 
causis by mere contact with oxygen, or by its fermenta- 
tion or putrefaction yields products possessed of this 
property. 

A small quantity of beer, acescent wine, a decoction 
of malt, honey, and numerous other substances of this 
kind, possess the action desired. 

The difference in the nature of the substances which 
possess this property shows, that none of them can con- 
tain a peculiar matter which has the property of exciting 
eremacausis ; they are only the bearers of an action, the 
influence of which extends beyond the sphere of its own 
attractions. Their power consists in a condition of de- 
composition or eremacausis, which impresses the same 
condition upon the atoms of alcohol in its vicinity ; ex- 
actly as in the case of an alloy of platinum and silver 
dissolving in nitric acid, in which the platinum becomes 
oxidized, by virtue of an inductive action which the 
silver in the act of its oxidation exercises upon it. The 
hydrogen of the alcohol is oxidized at the expense of the 
oxygen in contact with it, and forms water, evolving heat 
at the same time ; the residue is aldehyde, a substance 
which has as great an affinity for oxygen as sulphurous 
acid, and combines, therefore, directly with it, producing 
acetic acid. 



OF BODIES CONTAINING NITROGEN. 299 



CHAPTER VIII. 

EREMACAUSIS OF SUBSTANCES CONTAINING NITRO- 
GEN. NITRIFICATION. 

When azotized substances are burned at high tem- 
peratures, tlifiir nitrogen does not enter into direct com- 
bination with oxygen. The knowledge of this fact is of 
assistance in considering the process of the eremacausis 
of such substances. Azotized organic matter always 
contains carbon and hydrogen, both of which elements 
have a very strong affinity for oxygen. 

Now nitrogen possesses a very feeble affinity for that 
element, so that its compounds during their combustion 
present analogous phenomena to those which are observed 
in the combustion of substances containing a large pro- 
portion of hydrogen and carbon ; a separation of the 
carbon of the latter substances in an uncombined state 
takes place, and in the same way the substances con- 
taining nitrogen give out that element in its gaseous form. 

When a moist azotized animal matter is exposed to the 
action of the air, ammonia is always liberated, and nitric 
acid is never formed. 

But when alkalies or alkaline bases are present, a union 
of oxygen with the nitrogen lakes place under the same 
circumstances, and nitrates are formed together with the 
other products of oxidation. 

Although we see the most simple means and direct 
methods employed in the great processes of decomposition 
which proceed in nature, still we find that the final re- 
sult depends on a succession of actions, which are es- 
sentially influenced by the chemical nature of the bodies 
submitted to decomposition. 



300 EREMACAUSIS, OR DECAY, 

When it is observed that the character of a substance 
remains unaltered in a whole series of phenomena, there 
is no reason to ascribe a new character to it, for the 
purpose of explaining a single phenomenon, especially 
where the explanation of that according to known facts 
offers no difficulty. 

The most distinguished philosophers suppose that the 
nitrogen in an animal substance, when exposed to the 
action of air, water, and alkaline bases, obtains the 
power to unite directly with oxygen, and form nitric 
acid, but we are not acquainted with a single fact which 
justifies this opinion. It is only by the interposition of 
a large quantity of hydrogen in the stale of combustion 
or oxidation, that nitrogen can be converted into an 
oxide. 

When a compound of nitrogen and carbon, such as 
cyanogen, is burned in oxygen gas, its carbon alone is 
oxidized ; and when it is conducted over a metallic 
oxide heated to redness, an oxide of nitrogen is very 
rarely produced, and never when the carbon is in ex- 
cess. Kuhlmann found in his experiments, that it was 
only when cyanogen was mixed with an excess of oxy- 
gen gas, and conducted over spongy platinum, that 
nitric acid was generated. 

Kuhlmann could not succeed in causing pure nitrogen 
to combine directly with oxygen, even under the most 
favorable circumstances ; thus, vviih the aid of spongy 
platinum at different temperatures, no union took place. 

The carbon in the cyanogen gas must, therefore, 
have given rise to the combustion of the nitrogen by 
induction. 

On the other hand we find that ammonia, which is a 
compoufTd of hydrogen and nitrogen, cannot be exposed 



OF BODIES CONTAINING NITROGEN. 301 

to the action of oxygen, without the formation of an 
oxide of nitrogen, and in consequence the production of 
nitric acid. 

It is owing to the great facility with which ammonia 
is converted into nitric acid, that it is so difficult to ob- 
tain a correct determination of the quantity of nitrogen 
in a compound subjected to analysis, in which it is 
either contained in the form of ammonia, or from which 
ammonia is formed by an elevation of temperature. For 
when ammonia is passed over red-hot oxide of copper, 
it is converted either completely or partially, into bin- 
oxide of nitrogen. 

When ammoniacal gas is conducted over peroxide 
of manganese or iron heated to redness, a large quantity 
of nitrate of ammonia is obtained, if the ammonia be in 
excess ; and the same decomposition happens, when 
ammonia and oxygen are together passed over red-hot 
spongy platinum. 

It appears, therefore, that the combination of oxygen 
with nitrogen occurs rarely during the combustion of 
compounds of the latter element with carbon, but that 
nitric acid is always a product when ammonia is present 
in the substance exposed to oxidation. 

The cause wherefore the nitrogen in ammonia exhib- 
its such a strong disposition to become converted into 
nitric acid is undoubtedly, that the two products, which 
are the result of the oxidation of the constituents of am- 
monia, possess the power of uniting with one another. 
Now this is not the case in the combustion of com- 
pounds of carbon and nitrogen ; here one of the pro- 
ducts is carbonic acid, which on account of its gaseous 
form, must oppose the combination of the oxygen and 
nitrogen, by preventing their mutual contact, while the 
26 



302 EREMACAUSIS, OR DECAY. 

superior affinity of its carbon for the oxygen during the 
act of its formation will aid in this effect. 

When sufficient access of air is admitted during the 
combustion of ammonia, water is formed as well as 
nitric acid, and both of these bodies combine together. 
The presence of water may, indeed, be considered as 
one of the conditions df nitrification, since nitric acid 
cannot exist without it. 

Eremacausis is a kind of putrefaction, differing from 
the common process of putrefaction, only in the part 
which the oxygen of the air plays in the transformations 
of the body in decay. When this is remembered, and 
when it is considered, that in the transposition of the 
elements of azotized bodies their nitrogen assumes the 
form of ammonia, and that in this form, nitrogen pos- 
sesses a much greater disposition to unite with oxygen 
than it has in any of its other compounds ; we can with 
difficulty resist the conclusion, that ammonia is the gen- 
eral cause of nitrification on the surface of the earth. 

Azotized animal matter is not, therefore, the imme- 
diate cause of nitrification, it contributes to the produc- 
tion of nitric acid only in so far as it is a slow and 
continued source of ammonia. 

Now it has been shown in the former part of this 
work, that ammonia is always present in the atmo- 
sphere, so that nitrates might thence be formed in sub- 
stances which themselves contained no azotized matter. 
It is known also, that porous substances possess gener- 
ally the power of condensing ammonia ; there are few 
ferruginous earths which do not evolve ammoniacal pro- 
ducts when healed to redness, and ammonia is the 
cause of the peculiar smell perceived upon moistening 
aluminous minerals. Thus, ammonia, by being a con- 



VINOUS FERMENTATION. 303 

stituent of the atmosphere, is a very widely diffused 
cause of nitrification, which will come into play when- 
ever the different conditions necessary for the oxidation 
of ammonia are combined. It is probable that other 
organic bodies in the state of eremacausis are the means 
of causing the combustion of ammonia ; at all events, 
the cases are very rare, in which nitric acid is generat- 
ed from ammonia, in the absence of all matter capable 
of eremacausis. 

From the preceding observations on the causes of 
fermentation, putrefaction, and decay, we may now 
draw several conclusions calculated to correct the views 
generally entertained respecting the fermentation of 
wine and beer, and several other important processes of 
decomposition which occur in nature. 



CHAPTER IX. 

ON VINOUS fermentation: WINE AND BEER. 

It has already been mentioned, that fermentation is 
excited in the juice of grapes by the access of air ; 
alcohol and carbonic acid being formed by the decom- 
position of the sugar contained in the jfluid. But it was 
also stated, that the process once commenced, continues 
until all the sugar is completely decomposed, quite in- 
dependently of any further influence of the air. 

In addition to the alcohol and carbonic acid formed 
by the fermentation of the juice, there is also produced 
a yellow or gray insoluble substance, which contains a 
large quantity of nitrogen. It is this body which pos- 



304 VINOUS FERMENTATION. 

sesses the power of inducing fermentation in a new 
solution of sugar, and which has in consequence receiv- 
ed the name o{ ferment. 

The alcohol and carbonic acid are produced from 
the elements of the sugar, and the ferment from those 
azotized constituents of the grape juice, which have 
been termed gluten, or vegetable albumen. 

According to the experiments of De Saussure, fresh 
impure gluten evolved, in five weeks, twenty-eight times 
its volume of a gas of which 3 consisted of carbonic 
acid, and 5 of pure hydrogen gas ; ammoniacal salts of 
several organic acids were formed at the same time. 
Water must, therefore, be decomposed during the pu- 
trefaction of gluten ; the oxygen of this water must enter 
into combination with some of its constituents, whilst 
hydrogen is liberated, a circumstance which happens 
only in decompositions of the most energetic kind. 
Neither ferment nor any substance similar to it is form- 
ed in this case ; and we have seen that in the fermenta- 
tion of saccharine vegetable juices, no escape of hydro- 
gen gas takes place. 

It is evident that the decomposition which gluten 
suffers in an isolated state, and that which it undergoes 
when dissolved in a vegetable juice, belong to two dif- 
ferent kinds of transformations. There is reason to 
believe that its change to the insoluble state depends 
upon an absorption of oxygen, for its separation in this 
state may be effected under certain conditions, by free 
exposure to the air, without the presence of fermenting 
sugar. It is known also that the juice of grapes, or 
vegetable juices in general, become turbid when in con- 
tact with air, before fermentation commences ; and this 



YEAST FROM BEER AND WINE. 305 

turbidity is owing to the formation of an insoluble pre- 
cipitate of the same nature as ferment. 

From the phenomena which have been observed dur- 
ing the fermentation of wort,* it is known with perfect 
certainty that ferment is formed from gluten at the same 
time that the transformation of the sugar is effected ; 
for the wort contains the azotized matter of the corn, 
namely, gluten in the same condition as it exists in the 
juice of grapes. The wort ferments by the addition of 
yeast, but after its decomposition is completed, the 
quantity of ferment or yeast is found to be thirty times 
greater than it was originally. 

Yeast from beer and that from wine, examined under 
the microscope, present the same form and general 
appearance. They are both acted on in the same 
manner by alkalies and acids, and possess the power of 
inducing fermentation anew in a solution of sugar ; in 
short they must be considered as identical. 

The fact, that water is decomposed during the putre- 
faction of gluten has been completely proved. The 
tendency of the carbon of the gluten to appropriate the 
oxygen of water must also always be in action, whether 
the gluten is decomposed in a soluble or insoluble state. 
These considerations, therefore, as well as the circum- 
stance which all the experiments made on this subject 
appear to point out, that the conversion of gluten to the 
insoluble state is the result of oxidation, lead us to con- 
clude that the oxygen consumed in this process is de- 
rived from the elements of water, or from the sugar 
which contains oxygen and hydrogen in the same pro- 

* Wort is an infusion of malt ; it consists of insoluble parts of this 
substance dissolved in water. — Trans. 
26* 



306 VINOUS FERMENTATION. 

portion as water. At all events, the oxygen thus con- 
sumed in the fermentation of wine and beer is not taken 
from the atmosphere. 

The fermentation of pure sugar in contact with yeast 
must evidently be a very different process from the 
fermentation of wort or must.* 

In the former case, the yeast disappears during the 
decomposition of the sugar ; but in the latter, a trans- 
formation of glulen is effected at the same time, by 
which ferment is generated. Thus yeast is destroyed 
in the one case, but is formed in the other. 

Now since no free hydrogen gas can be detected 
during the fermentation of beer and wine, it is evident 
that the oxidation of the gluten, that is, its conversion 
into ferment, must take place at the cost either of the 
oxygen of the water, or of that of the sugar ; whilst the 
hydrogen which is set free must enter into new combi- 
nations, or by the deoxidation of the sugar, new com- 
pounds containing a large proportion of hydrogen, and 
small quantity of oxygen, together with the carbon of 
the sugar, must be formed. 

It is well known that wine and fermented liquors 
generally contain, in addition to the alcohol, other sub- 
stances which could not be detected before their fer- 
mentation, and which must have been formed, therefore, 
during that process in a manner similar to the produc- 
tion of mannite. The smell and taste which distinguish 
wine from all other fermented liquids are known to de- 
pend upon an ether of a volatile and highly combustible 
acid, which is of an oily nature, and to which the name 
of (Enanthic ether has been given. It is also ascertain- 

* The liquid expressed from grapes when fully ripe is called must. 



OILY AND ETHEREAL PRODUCTS. 307 

ed that the smell and taste of brandy from corn and 
potatoes is owing to a peculiar oil, the oil of potatoes. 
This oil is more closely allied to alcohol in its proper- 
ties, than to any other organic substance. 

These bodies are products of the deoxidation of the 
substances dissolved in the fermenting liquids ; they 
contain less oxygen than sugar or gluten, but are re- 
markable for the large quantity of hydrogen which en- 
ters into their composition. 

CEnanthic acid contains an equal number of equiva- 
lents of carbon and hydrogen, exactly the same propor- 
tions of these elements, therefore, as sugar, but by no 
means the same proportion of oxygen. The oil of 
potatoes contains much more hydrogen. 

Although it cannot be doubted that these volatile 
liquids are formed by a mutual interchange of the ele- 
ments of gluten and sugar, in consequence, therefore, 
of a true process of putrefaction, still it is certain, that 
other causes exercise an influence upon their production 
and peculiarities. 

The substances in wine to which its taste and smell 
are owing are generated during the fermentation of the 
juice of such grapes as contain a certain quantity of 
tartaric acid ; they are not found in wines which are 
free from all acid, or which contain a different organic 
acid, such as acetic acid. 

The wines of warm climates possess no odor ; wines 
grown in France have it in a marked degree, but in the 
wines from the Rhine the perfume is most intense. 
The kinds of grapes on the Rhine, which ripen very 
late, and scarcely ever completely, such as the Reiss- 
ling and Orleans^ have the strongest perfume or bou- 
quet^ and contain, proportionally, a larger quantity of 



308 VINOUS FERMENTATION. 

tartaric acid. The earlier grapes, such as the Ruldn- 
der and others, contain a large proportion of alcohol, 
and are similar to Spanish wines in their flavor, but 
they possess no bouquet. 

The grapes grown at the Cape from Riesslings trans- 
plated from the Rhine, produce an excellent wine, 
which does not however possess the aroma which dis- 
tinguishes Rhenish wine. 

It is evident from these facts, that the acid of wines, 
and their characteristic perfumes, have some connex- 
ion, for they are always found together, and it can 
scarcely be doubted that the presence of the former 
exercises a certain influence on the formation of the 
latter. This influence is very plainly observed in the 
fermentation of liquids, which are quite free from tar- 
taric acid, and particularly of those which are nearly 
neutral or alkaline, such as the mash* of potatoes or 
corn. 

The brandy obtained from corn and potatoes con- 
tains an ethereal oil of a similar composition in both, to 
which these liquors owe their peculiar smell. This oil 
is generated during the fermentation of the mash; it ex- 
ists ready formed in the fermented liquids, and distils 
over with alcohol, when a gentle heat is applied. 

It is observed that a greater quantity of alcohol is 
obtained when the mash is made quite neutral by means 
of ashes or carbonate of lime, but that the proportion of 
oil in the brandy is also increased. 

Now it is known that brandy made from potato 
starch, which has been converted into sugar by dilute 



* Mash is the mixture of malt, potatoes, and water, in the mask 
tun, a large vessel in which it is infused. — Trans. 



OILr AND ETHEREAL PRODUCTS. 309 

sulphuric acid, is completely free from ihe potato oil, 
so that this substance must be generated in consequence 
of a change suffered by the cellular tissue of the pota- 
toes during their fermentation. 

Experience has shown that the simultaneous fermen- 
tation or putrefaction of the cellular tissue, by which 
this oil is generated, may be completely prevented in 
the fabrication of brandy from corn.* 

The same malt, which in the preparation of brandy 
yields a fluid containing the oil of which we are speak- 
ing, affords in the formation of beer a spirituous liquor, 
in which no trace of that oil can be detected. The 
principal difference in the preparation of the two liquids 
is, that in the fermentation of wori^ an aromatic sub- 
stance [hops] is added, and it is certain that its pres- 
ence modifies the transformations which take place. 
Now it is known, that the volatile oil of mustard, and 
the empyreumatic oils, arrest completely the action of 
yeast ; and although the oil of hops does not possess 
this property, still it diminishes, in a great degree, the 
influence of decomposing azotized bodies upon the con- 
version of alcohol into acetic acid. There is, therefore, 
reason to believe that some aromatic substances, when 
added to fermenting mixtures, are capable of producing 
very various modifications in the nature of the products 
generated. 

Whatever opinion, however, may be held regarding 
the origin of the volatile odoriferous substances obtained 
in the fermentation of wine, it is quite certain that the 

* In the manufactory of M. Diibrunfaut, so considerable a quan- 
tity of this oil is obtained under certain circumstances from brandy 
made from potatoes, that it might be employed for the purpose of illu- 
minating his whole manufactory. — L. 



310 VINOUS FERMENTATION. 

characteristic smell of wine is owing to an ether of an 
organic acid, resembhng one of the fatty acids. 

It is only in liquids which contain other very soluble 
acids, that the fatty acids and oenanthic acid are capable 
of entering into combination with the ether of alcohol, 
and of thus producing compounds of a peculiar smell. 
This ether is found in all wines which contain free acid, 
and is absent from those in which no acids are present. 
This acid, therefore, is the means by which the smell is 
produced ; since without its presence cenanthic ether 
could not be formed. 

The greatest part of the oil of brandy made from 
corn consists of a fatty acid not converted into ether ; 
it dissolves oxide of copper and metallic oxides in gen- 
eral, and combines with the alkalies. 

The principal constituent of this oil is an acid identi- 
cal in composition with oenanthic acid, but different in 
properties (Mulder). It is formed in fermenting liquids, 
which, if they be acid, contain only acetic acid, a body 
which has no influence in causing other acids to form 
ethers. 

The oil of brandy made from potatoes is the hydrate 
of an organic base analogous to ether, and capable, 
therefore, of entering into combination with acids. It 
is formed in considerable quantity in fermenting liquids 
which are slightly alkaline, under circumstances, conse- 
quently, in which it is incapable of combining with an 
acid. 

The products of the fermentation and putrefaction of 
neutral vegetable and animal matters, are generally ac- 
companied by substances of an offensive odor ; but the 
most remarkable example of the generation of a true 
ethereal oil, is seen in the fermentation of the Hcrba 



ODORIFEROUS PRODUCTS. 311 

centaurium minorius^ a plant which possesses no smell. 
When it is exposed in water to a slightly elevated tem- 
perature it ferments, and emits an agreeable penetrating 
odor. By the distillation of the hquid, an ethereal oily 
substance of great volatility is obtained, which excites a 
pricking sensation in the eyes, and a flow of tears 
(^Bilchner) . 

The leaves of the tobacco plant present the same 
phenomena ; when fresh, they possess very little or no 
smell. When they are subjected to distillation with 
water, a weak ammoniacal liquid is obtained, upon 
which a white fatty crystallizable substance swims, 
which does not contain nitrogen, and is quite destitute 
of smell. But when the same plant, after being dried, 
is moistened with water, tied together in small bundles, 
and placed in heaps, a peculiar process of decomposition 
takes place. Fermentation commences, and is accom- 
panied by the absorption of oxygen ; the leaves now 
become warm and emit the characteristic smell of pre- 
pared tobacco and snufF. When the fermentation is 
carefully promoted and too high a heat avoided, this 
smell increases and becomes more delicate ; and after 
the fermentation is completed, an oily azotized volatile 
matter called nicotine is found in the leaves. This sub- 
stance, — nicotine.^ which possesses all the properties of 
a base, was not present before the fermentation. The 
different kinds of tobacco are distinguished from one 
another, like wines, by having very different odoriferous 
substances, which are generated along with the nico- 
tine. 

We know that most of the blossoms and vegetable 
substances which possess a smell, owe this property to 
a volatile oil existing in them ; but it is not less certain. 



312 VINOUS FERMENTATION. 

that others emit a smell only when they undergo change 
or decomposition. 

Arsenic and arsenious acid are both quite inodorous. 
It is only during their oxidation that they emit their 
characteristic odor of garlic. The oil of the berries of 
the elder tree, many kinds of oil of turpentine, and oil 
of lemons, possess a smell only during their oxidation or 
decay. The same is the case with many blossoms ; and 
Geiger has shown, that the smell of musk is owing to 
its gradual putrefaction and decay. 

It is also probable, that the peculiar odorous principle 
of many vegetable substances is newly formed during 
the fermentation of the saccharine juices of the plants. 
At all events, it is a fact, that very small quantities of 
the blossoms of the violet, elder, linden, or cowslip, 
added to a fermenting liquid, are sufficient to communi- 
cate a very strong taste and smell, which the addition of 
the water distilled from a quantity a hundred times 
greater would not affect. The various kinds of beer 
manufactured in Bavaria are distinguished by different 
flavors, which are given by allowing small quantities of 
the herbs and blossoms of particular plants to ferment 
along with the wort. On the Rhine, also, an artificial 
bouquet is often given to wine for fraudulent purposes, by 
the addition of several species of the sage and rue to the 
fermenting liquor ; but the perfumethus obtained differs 
from the genuine aroma, by its inferior durability, it be- 
ing gradually dissipated. 

The juice of grapes grown in different climates dif- 
fers not only in the proportion of free acid which it con- 
tains, but also in respect of the quantity of sugar dis- 
solved in it. The quantity of azotized matter in the 
juice seems to be the same in whatever part the grapes 



i 



VARIOUS PROPERTIES OF WINES. 313 

may grow ; at least no difference has been observed in 
the amount of yeast fornned during fernnentation in the 
south of France, and on the Rhine. 

The grapes grown in hot chmates, as well as the 
boiled juice obtained from them, are proportionally rich 
in sugar. Hence, during the fermentation of the juice, 
the complete decomposition of its azotized matters, and 
their separation in the insoluble state, are effected before 
all the sugar has been converted into alcohol and car- 
bonic acid. A certain quantity of the sugar consequent- 
ly remains mixed with the wine in an undecomposed 
state, the condition necessary for its further decomposi- 
tion being absent. 

The azotized matters in the juice of grapes of the 
temperate zones, on the contrary, are not completely 
separated in the insoluble state, when the entire transfor- 
mation of the sugar is effected. The wine of these 
grapes, therefore, does not contain sugar, but variable 
quantities of undecomposed gluten in solution. 

This gluten gives the wine the property of becoming 
spontaneously converted into vinegar, when the access 
of air is not prevented. For it absorbs oxygen and be- 
comes insoluble ; and its oxidation is communicated to 
the alcohol, which is converted inlo acetic acid. 

By allowing the wine to remain at rest in casks with 
a very limited access of air, and at the lowest possible 
temperature, the oxidation of this azotized matter is ef- 
fected without the alcohol undergoing the same change, 
a higher temperature being necessary to enable alcohol 
to combine with oxygen. As long as the wine in the 
s^^7/mo•-ccr.s/(:5 deposits yeast, it can still be caused to fer- 
ment by the addition of sugar, but old well-layed wine- 
has lost this property, because the condition necessary 
27 



314 FERMENTATION OF BEER. 

for fermentation, namely, a substance in the act of de- 
composition or putrefaction, is no longer present in it. 

In hotels and other places where the wine is drawn 
gradually from a cask, and a proportional quantity of air 
necessarily introduced, its eremacausis, that is, its conver- 
sion into acetic acid, is prevented by the addition of a 
small quantity of sulphurous acid. This acid, by uniting 
itself with the oxygen of the air contained in the cask, 
or dissolved in the wine, prevents the oxidation of the 
organic matter. 

The various kinds of beer differ from one another in 
the same way as the wines. 

English, French, and most of the German beers, are 
converted into vinegar when exposed to the action of 
air. But this property is not possessed by Bavarian 
beer, which may be kept in vessels only half-filled with- 
out acidifying or experiencing any change. This valua- 
ble quality is obtained for it by a peculiar management 
of the fermentation of the wort. The perfection of ex- 
perimental knowledge has here led to the solution of one 
of the most beautiful problems of the theory of fermen- 
tation. 

Wort is proportionally richer in gluten than in sugar, 
so that during its fermentation in the common way, a 
great quantity of yeast is formed as a thick scum. The 
carbonic acid evolved during the process attaches itself 
to the particles of the yeast, by which they become spe- 
cifically lighter than the liquid in which they are formed, 
and rise to its surface. Gluten in the act of oxidation 
comes in contact with the particles of the decomposing 
sugar in the interior of the liquid. The carbonic acid 
from the sugar, and insoluble ferment from the gluten, 
are disen"ao;ed simultaneously, and co!:ere together. 



THE BAVARIAN PROCESS. 315 

A great quantity of gluten remains dissolved in the 
fermented liquid, even after the transformation of the su- 
gar is completed, and this gluten causes the conversion 
of the alcohol into acetic acid, on account of its strong 
disposition to attract oxygen, and to undergo decay. 
Now, it is plain, that with its separation, and that of all 
substances capable of attracting oxygen, the beer would 
lose the property of becoming acid. This end is com- 
pletely attained in the process of fermentation adopted in 
Bavaria. 

The wort, after having been treated with hops in the 
usual manner, is thrown into very wide, flat vessels, in 
which a large surface of the liquid is exposed to the air. 
The fermentation is then allowed to proceed while the 
temperature of the chambers in which the vessels are 
placed, is never allowed to rise above from 45° to 50^ 
F. The fermentation lasts from three to six weeks, and 
the carbonic acid evolved during its continuance is not 
in large bubbles which burst upon the surface of the li- 
quid, but in small bubbles like those which escape from 
a liquid saturated by high pressure. The surface of the 
wort is scarcely covered with a scum, and all the yeast 
is deposited on the bottom of the vessel in the form of a 
viscous sediment. 

In order to obtain a clear conception of the great dif- 
ference between the two kinds of fermentation, it may 
perhaps be sufficient to recall to mind the fact, that the 
transformation of gluten or other azotized matters is a 
process consisting of several stages. The first stage is 
the conversion of the gluten into insoluble ferment in the 
interior of the liquid, and as the transformation of the su- 
gar goes on at the same time, carbonic acid and yeast are 
simultaneously disengaged. It is known with certainty, 



316 FERMENTATION OF BEER. 

that this formation of yeast depends upon oxygen being 
appropriated by the gluten in the act of decomposition ; 
but it has not been sufficiently shown, whether this oxy- 
gen is derived from the water, sugar, or from the gluten 
itself; whether it combines directly with the gluten, or 
merely with its hydrogen, so as to form water. For the 
purpose of obtaining a definite idea of the process, we 
may designate the first change as the stage of oxidation. 
This oxidation of the gluten then, and the transposition 
of the atoms of the sugar into alcohol and carbonic acid, 
are necessarily attendant on each other, so that if the one 
is arrested the other must also cease. 

Now, the yeast which rises to the surface of the liquid 
is not the product of a complete decomposition, but is 
oxidized gluten still capable of undergoing a new trans- 
formation by the transposition of its constituent elements. 
By virtue of this condition, it has the power to excite fer- 
mentation in a solution of sugar ; and if gluten be also 
present, the decomposing sugar induces its conversion 
into fresh yeast, so that, in a certain sense, the yeast ap- 
pears to reproduce itself. 

Yeast of this kind is oxidized gluten in a state of pu- 
trefoction, and by virtue of this state it induces a similar 
transformation in the elements of the sugar. 

The yeast formed during the fermentation of Bavarian 
beer is oxidized gluten in a state of decay. The process 
of decomposition which its constituents are suffering, 
gives rise to a very protracted putrefaction (^fermenta- 
tioii) in the sugar. The intensity of the action is di- 
minished in so great a degree, that the gluten which the 
fluid still holds in solution takes no part in it ; the sugar 
in fermentation does not excite a similar state in the glu- 
ten. 



THE BAVARIAN PROCESS. 317 

But the contact of the already decaying and precipi- 
tated gluten or yeast, causes the eremacausis of the glu- 
ten dissolved in the wort ; oxygen gas is absorbed from 
the air, and all the gluten in solution is deposited as 
yeast. 

The ordinary frothy yeast may be removed from fer- 
menting beer by filtration, without the fermentation being 
thereby arrested ; but precipitated yeast of Bavarian beer 
cannot be removed without the whole process of its fer- 
mentation being interrupted. The beer ceases to fer- 
ment altogether, or, if the temperature is raised, under- 
goes the ordinary fermentation. 

The precipitated yeast does not excite ordinary fer- 
mentation, and consequently is quite unfitted for the pur- 
pose of baking, but the common frothy yeast can cause 
the kind of fermentation by which the former kind of 
yeast is produced. 

When comtnon yeast is added to wort at a tempera- 
ture of between 40^ and 45"^ F., a slow, tranquil fer- 
mentation takes place, and a matter is deposited on the 
bottom of the vessel, which may be employed to excite 
new fermentation ', and when the same operation is re- 
peated several times in succession, the ordinary fermenta- 
tion changes into that process by which only precipitat- 
ed yeast is formed. The yeast now deposited has lost 
the property of exciting ordinary fermentation, but it 
produces the other process even at a temperature of 
50° F. 

In wort subjected to fermentation, at a low tempera- 
ture, with this kind of yeast, the condition necessary for 
the transformation of the sugar is the presence of that 
yeast ; but for the conversion of gluten into ferment by 
a process of oxidation, something more is required. 
27* 



318 FERMENTATION OF BEER. 

When the power of gluten to attract oxygen is in- 
creased by contact with precipitated yeast in a slate of 
decay, the unrestrained access of air is the only other 
condition necessary for its own conversion into the same 
state of decay, that is for its oxidation. We have 
already seen that the presence of free oxygen and gluten 
are conditions which determine the eremacausis of alco- 
hol and its conversion into acetic acid, but they are 
incapable of exerting this influence at low temperatures. 
A low temperature retards the slow combustion of alco- 
hol, while the gluten combines spontaneously with the 
oxygen of the air, just as sulphurous acid does when 
dissolved in water. Alcohol undergoes no such change 
at low temperatures, but during the oxidation of the 
gluten in contact with it, is in the same condition as the 
gluten itself is placed in when sulphurous acid is added 
to the wine in which it is contained. The oxygen of 
the air unites both with the gluten and alcohol of wine 
not treated with sulphurous acid, but when this acid is 
present it combines with neither of them, being alto- 
gether absorbed by the acid. The same thing happens 
in the peculiar process of fermentation adopted in Ba- 
varia. The oxygen of the air unites only with the gluten 
and not with the alcohol, although it would have com- 
bined with both at higher temperatures, so as to form 
acetic acid. 

Thus, then, this remarkable process of fermentation 
with the precipitation of a mucous-like ferment consists 
of a simultaneous putrefaction and decay in ihe same 
liquid. The sugar is in the state of putrefaction, and 
the gluten in that of decay. 

Jippert''s method of preserving food (p. 294), and this 
kind of fermentation of beer, depend on the same prin- 
ciple. 



THE BAVARIAN PROCESS. 319 

In the fermentation of beer after this manner, all the 
substances capable of decay are separated from it by 
means of an unrestrained access of air, while the tempera- 
ture is kept sufficiently low to prevent the alcohol from 
combining with oxygen. The removal of these sub- 
stances diminishes the tendency of the beer to become 
acescent, or, in other words, to suffer a further trans- 
formation. 

In JlpperVs mode of preserving food, oxygen is al- 
lowed to enter into combination with the substance of 
the food, at a temperature at which decay, but neither 
putrefaction nor fermentation can take place. With the 
subsequent exclusion of the oxygen and the completion 
of the decay, every cause which could effect further de- 
composition of the food is removed. The conditions 
for putrefaction are rendered insufficient in both cases ; 
in the one by the removal of the substances susceptible 
of decay, in the other by the exclusion of the oxygen 
which would effect it. 

It has been stated (page 316) to be uncertain, whether 
gluten during its conversion into common yeast, that is, 
into the insoluble state in which it separates from fer- 
menting liquids, really combines directly with oxygen. 
If it does combine with oxygen, then the difference be- 
tween gluten and ferment would be, that the latter would 
contain a larger proportion of oxygen. Now it is very 
difficult to ascertain this, and even their analyses cannot 
decide the question. Let us consider, for example, the 
relations of alloxan and alloxantin * to one another. Both 
of these bodies contain the same elements as gluten. 



* Products of the decomposition of uric acid by nitric acid, consist- 
ing of carbon, nitrogen, hydrogen, and oxygen. See description, &c. 
in Webster's Chemistry, pp. 425, 430. 



320 FERMENTATION OF BEER. 

although in different proportions. Now they are known 
to be convertible into each other, by oxygen being ab- 
sorbed in the one case, and in the other extracted. 
Both are composed of absolutely the same elements, in 
equal proportions ; with the single exception, that allox- 
antin contains 1 equivalent of hydrogen more than al- 
loxan. 

When alloxantin is treated with chlorine and nitric 
acid, it is converted into alloxan, into a body, therefore, 
which is alloxantin minus 1 equivalent of hydrogen. If 
on the other hand a stream of sulphuretted hydrogen is 
conducted through alloxan, sulphur is precipitated, and 
alloxantin produced. It may be said, that in the first 
case hydrogen is abstracted, in the other added. But it 
would be quite as simple an explanation, if we consid- 
ered them as oxides of the same radical ; the alloxan 
being regarded as a combination of a body composed of 
C8 N2 H2 OS with 2 equivalents of water, and alloxan- 
tin as a combination of 3 atoms of water, with a com- 
pound consisting of C8 N2 H2 07. The conversion of 
alloxan into alloxantin would in this case result from its 
eight atoms of oxygen being reduced to seven, while 
alloxan would be formed out of alloxantin, by its com- 
bining with an additional atom of oxygen. 

Now, oxides are known which combine with water, 
and present the same phenomena as alloxan and alloxan- 
tin. But no compounds of hydrogen are known which 
form hydrates ; and custom, which rejects all dissim- 
ilarity until the claim to peculiarity is quite proved, leads 
us to prefer an opinion, for which there is no further 
foundation than that o( analogy. The woad {Isatis tinc- 
toria) and several species of the J^erium contain a sub- 
stance similar in many respects to gluten, which is 



THE BAVARIAN PROCESS. 321 

deposited as indigo blue, when an aqueous infusion of 
the dried leaves is exposed to the action of the air. 
Now it is very doubtful whether the blue insoluble indi- 
go is an oxide of the colorless soluble indigo, or the 
latter a combination of hydrogen with the indigo blue. 
Dumas has found the same elements in both, except that 
the soluble compound contained 1 equivalent of hydro- 
gen more than the blue. 

In the same manner the soluble gluten may be con- 
sidered a compound of hydrogen, which becomes fer- 
ment by losing a certain quantity of this element when 
exposed to the action of the oxygen of the air under 
favorable circumstances. At all events, it is certain 
that oxygen is the cause of the insoluble condition of 
gluten ; for yeast is not deposited on keeping wine, or 
during the fermentation of Bavarian beer, unless oxygen 
has access to the fluid. 

Now whatever be the form in which the oxygen 
unites with the gluten, — whether it combines directly 
with it or extracts a portion of its hydrogen, forming 
water, — the products formed in the interior of the 
liquid, in consequence of the conversion of the gluten 
into ferment, will still be the same. Let us suppose 
that gluten is a compound of another substance with hy- 
drogen, then this hydrogen must be removed during the 
ordinary fermentation of must and ivort, by combining 
with oxygen, exactly as in the conversion of alcohol into 
aldehyd * by eremacausis. 

In both cases the atmosphere is excluded ; the oxy- 

* A liquid having a peculiar ethereal smell, and obtained by passing 
the vapor of ether through a large glass tube heated to redness, and 
by other processes. It consists of carbon 4, hydrogen 4, oxygen 2. 
Its name is from the Latin, alcohol dehydratus. 



322 FERMENTATION OF BEER. 

gen cannot, then, be derived from the air, neither can it 
be supplied by the elements of water, for it is impossi- 
ble to suppose that the oxygen will separate from the 
hydrogen of water, for the purpose of uniting with the 
hydrogen of gluten, in order again to form water. The 
oxygen must, therefore, be obtained from the elements 
of sugar, a portion of which substance must, in order to 
the formation of ferment, undergo a different decompo- 
sition from that which produces alcohol. Hence a cer- 
tain part of the sugar will not be converted into carbonic 
acid and alcohol, but will yield other products contain- 
ing less oxygen than sugar itself contains. These pro- 
ducts, as has already been mentioned, are the cause of 
the great difference in the qualities of fermented liquids, 
and particularly in the quantity of alcohol which they 
contain. 

Must and wort do not, therefore, in ordinary fermen- 
tation, yield alcohol in proportion to the quantity of 
sugar which they hold in solution, a part of the sugar 
being employed in the conversion of gluten into fer- 
ment, and not in the formation of alcohol. But in the 
fermentation of Bavarian beer all the sugar is expended 
in the production of alcohol ; and this is especially the 
case whenever the transformation of the sugar is not ac- 
companied by the formation of yeast. 

It is quite certain that in the distilleries of brandy 
from potatoes, where no yeast is formed, or only a 
quantity corresponding to the malt which has been add- 
ed, the proportion of alcohol and carbonic acid obtain- 
ed during the fermentation of the mash corresponds 
exactly to that of the carbon contained in the starch. 
It is also known that the volume of carbonic acid evolv- 
ed during the fermentation of beet-roots gives no exact 



THE BAVARIAN PROCESS. 323 

indication of the proportion of sugar contained in ihenm,. 
lor less carbonic acid is obtained than the same quantity 
of pure sugar would yield. 

Beer obtained by the mode of fermentation adopted 
in Bavaria contains more alcohol, and possesses more 
intoxicating properties, than that made by the ordinary 
method of fermentation, when the quantities of malt used 
are the same. The strong taste of the former beer is 
generally ascribed to its containing carbonic acid in 
larger quantity, and in a state of more intimate combi- 
nation ; but this opinion is erroneous. Both kinds of 
beer are, at the conclusion of the fermentation, com- 
pletely saturated with carbonic acid, the one as much 
as the other. Like all other liquids, they must both 
retain such a portion of the carbonic acid evolved as 
corresponds to their power of solution, that is, to their 
volumes. 

The temperature of the fluid during fermentation has 
a very important influence on the quantity of alcohol 
generated. It has been mentioned, that the juice of 
beet-roots allowed to ferment at from 86^ to 95° (30° 
to 35° C.) yields no alcohol ; and that afterwards, in the 
place of the sugar, mannite, a substance incapable of 
fermentation, and containing very little oxygen, is found, 
together with lactic acid and mucilage. The formation 
of these products diminishes in proportion as the tem- 
perature is lower. But in vegetable juices, containing 
nitrogen, it is impossible to fix a liniit, where the trans- 
formation of the sugar is undisturbed by any other pro- 
cess of decomposition. 

It is known that in the fermentation of Bavarian beer 
the action of the oxygen of the air, and the low temper- 
ature, cause complete transformation of the sugar into 



324 FERMENTATION OF BEER. 

alcohol ; the cause which would prevent that result, 
namely, the extraction of the oxygen of part of the sugar 
by the gluten, in its conversion into ferment, being 
avoided by the introduction of oxygen from without. 

The quantity of matters in the act of transformation 
is naturally greatest at the beginning of the fermentation 
of must and wort ; and all the phenomena which accom- 
pany the process, such as evolution of gas, and heat, 
are best observed at that time. These signs of the 
changes proceeding in the fluid diminish when the 
greater part of the sugar has undergone decomposition ; 
but they must cease entirely before the process can be 
regarded as completed. 

The less rapid process of decomposition which suc- 
ceeds the violent evolution of gas, continues in wine 
and beer until the sugar has completely disappeared ; 
and hence it is observed, that the specific gravity of the 
liquid diminishes during many months. This slow fer- 
mentation, in most cases, resembles the fermentation of 
Bavarian beer, the transformation of the dissolved sugar 
being in \favt the result of a slow and continued decom- 
position of the precipitated yeast ; but a complete sep- 
aration of the azotized substances dissolved in it cannot 
take place when air is excluded. * 

* The great influence which a rational management of fermenta- 
tion exercises upon tlie quality of beer is well known in several of the 
German states. In the grand-duchy of Hesse, for example, a consid- 
erable premium is offered for the preparation of beer, according to 
the Bavarian method ; and the premium is to be adjudged to any one 
who can prove that the beer brewed by him has lain for six months 
in the store-vats without becoming acid. Hundreds of casks of beer 
became changed to vinegar before an empirical knowledge of those 
conditions was obtained, the influence of which is rendered intelligi- 
ble by the theory. 

Neither alcohol alone, nor hops, nor indeed both together, preserve 



MOULDERING OF VEGETABLE SUBSTANCES. 325 



CHAPTER X. 

ON THE MOULDERING OF BODIES. PAPER, BROWN 

COAL, AND MINERAL COAL. 

The decomposition of wood, woody fibre, and all 
vegetable bodies when subjected to the action of water, 
and excluded from the air, is termed mouldering. 

Wood or brown coal and mineral coal, are the re- 
mains of vegetables of a former world ; their appearance 
and characters show, that they are products of the pro- 
cesses of decomposition termed decay and putrefac- 
tion. We can easily ascertain by analysis the manner 
in which their constituents have been changed, if we sup- 
pose the greater part of their bulk to have been formed 
from woody fibre. 

But it is necessary before we can obtain a distinct idea 
of the manner in which coal is formed, to consider a pe- 
culiar change which woody fibre suffers by means of 
moisture, when partially or entirely excluded from the 
air. 

It is known, that when pure woody fibre, as linen, for 

beer from becoming acid. The better kinds of ale and porter in 
England are protected from acidity, but at the loss of the interest of 
an immense capital. They are placed in large closed wooden vessels, 
the surfaces of which are covered with sand. In these they are 
allowed to lie for several years, so that they are treated in a manner 
exactly similar to wine during its ripening. 

A gentle diffusion of air takes place through the pores of the wood» 
but the quantity of azotized substances being very great in proportioa 
to the oxygen which enters, they consume it, and prevent its union 
with the alcohol. But the beer treated in this way does not keep for 
two months without acidifying, if it be placed in smaller vessels, ta 
which free access of the air is permitted. — L. 

28 



326 DECOMPOSITION OF WOOD, COAL, &C. 

example, is placed in contact with water, considerable 
heat is evolved, and the substance is converted into a 
soft friable mass which has lost all coherence. This 
substance was employed in the fabrication of paper before 
the use of chlorine, as an agent for bleaching. The rags 
employed for this purpose were placed in heaps, and it 
was observed, that on their becoming warm a gas was 
disengaged, and their weight diminished from 18 to 25 
per cent. 

When sawdust moistened with water is placed in a 
closed vessel, carbonic acid gas is evolved in the same 
manner as when air is admitted. A true putrefaction 
takes place, the wood assumes a white color, loses its 
peculiar texture, and is converted into a rotten friable 
matter. 

The white decayed wood found in the interior of 
trunks of dead trees which have been in contact with 
water, is produced in the way just mentioned. 

An analysis of wood of this kind, obtained from the 
interior of the trunk of an oak, yielded, after having been 
dried at 212°, 

Carbon, . . 47.11 . . 4814 

Hydrogen, . . 6.31 . . 6.06 

Oxygen, . . 45.31 . . 44.43 

Ashes, . . 1.27 . . • 1.37 

100.00 100.00 

Now, on comparing the proportions obtained from 
these numbers with the composition of oak wood, ac- 
cording to the analysis of Gay-Lussac and Thenard, 
it is immediately perceived, that a certain quantity of 
carbon has been separated from the constituents of wood, 
whilst the hydrogen is, on the contrary, increased.* 

* The numbers obtained by the analysis correspond very nearly to 



IN CONTACT WITH WATER. 327 

The elements of water have, therefore, become united 
with the wood, whilst carbonic acid is disengaged by the 
absorption of a certain quantity of oxygen. 

If the elements of 5 atoms of water and 2 atoms of 
oxygen be added to the composition of the woody fibre 
of the oak, and 3 atoms of carbonic acid deducted, the 
exact formula for white mouldered wood is obtained. 

Wood, C36H22 022 

To this add 5 atoms of water, . . . H 5 O 5 

3 atoms of oxygen, O 3 

C36 H27 O30 
Subtract from this 3 atoms Carbonic acid, C 3 6 



C33 H27 024 



The process of mouldering is, therefore, one of putre- 
faction and decay, proceeding simultaneously, in which 
the oxygen of the air and the component parts of water 
take part. But the composition of mouldered wood 
must change according as the access of oxygen is more 
or less prevented. White mouldered beech wood yield- 
ed on analysis 47.67 carbon, 5.67 hydrogen, and 46.68 
oxygen ; this corresponds to the formula C33 H25 024. 

The decomposition of wood assumes, therefore, two 
different forms, according as the access of the air is free 
or restrained. In both cases carbonic acid is generated; 
and in the latter case, a certain quantity of water enters 
into chemical combination. 

It is highly probable that in this putrefactive process, 
as well as in all others, the oxygen of the water assists in 
the formation of the carbonic acid. 

Wood-coal (brown coal of Werner) must have been 

the formula C33 H27 024. (The calculation from this formula gives 
in 100 parts 47.9 carbon, 6.1 hydrogen, and 46 oxygen.) — L. 



328 CONVERSION OF WOOD 

produced by a process of decomposition similar to that 
of mouldering. But it is not easy to obtain wood-coal 
suited for analysis, for it is generally impregnated with 
resinous or earthy substances, by which the composition 
of those parts which have been formed from woody fibre 
is essentially changed. 

The wood-coal which forms extensive layers in the 
Weiterau (a district in Hesse Darmstadt), is distinguish- 
ed from that found in other places, by possessing the 
structure of wood unchanged, and by containing no bitu- 
minous matter. This coal was subjected to analysis, a 
piece being selected upon which the annual circle could 
be counted. It was obtained from the vicinity of Lau- 
bach ; 100 parts contained 

Carbon, 57.28 

Hydrogen, ..... 6.03 

Oxygen, ..... 36.10 

Ashes, 0.59 

100.00 

The large amount of carbon, and small quantity of 
oxygen, constitute the most obvious difference between 
this analysis and that of wood. It is evident that the 
wood which has undergone the change into coal must 
have parted with a certain portion of its oxygen. The 
proportion of these numbers is expressed by the formu- 
la C33 H21 016. (The calculation gives 57.5 carbon 
and 5.98 hydrogen.) 

When these numbers are compared with those obtain- 
ed by the analysis of oak, it would appear that the brown 
coal was produced from woody fibre by the separation of 
one equivalent of hydrogen, and the elements of three 
equivalents of carbonic acid. 



INTO BROWN OR WOOD COAL. 329 

1 atom wood, C36 H22 022 

Minus 1 atom hydrogen and 3 atoms carbonic acid, C 3H 1 O 6 



Wood-Coal. C33 H21 OIG 

All varieties of wood-coal, from whatever strata they 
may be taken, contain more hydrogen than wood does, 
and less oxygen than is necessary to form water with this 
hydrogen ; consequently they must all be produced by 
the same process of decomposition. The excess of hy- 
drogen is either hydrogen of the wood which has re- 
mained in it unchanged, or it is derived from some ex- 
terior source. The analysis of wood-coal from Ringkuhl, 
near Cassel, where it is seldom found in pieces with the 
structure of wood, gave, when dried at 212°, 



Carbon, 


62.60 


63.83 


Hydrogen, 


. 5.02 


. 4 80 


Oxygen, . 


26.52 


25.51 


Ashes, 


. 5.86 


. 5.86 



100.00 100.00 

The proportions derived from these numbers corre- 
spond very closely to the formula, Co2 Hi 5 09, or they 
represent the constituents of wood, from which the ele- 
ments of carbonic acid, water, and 2 equivalents hydro- 
gen have been separated. 

C36 H22 022 = Wood. 
Subtract C 4 H 7 013 = 4 atoms carbonic acid -f- 5 atoms of water 
-f-2 atoms of hydrogen. 



C32 H15 = Wood-Coal from Ringkuhl. 

The formation of both these specimens of wood-coal 
appears from these formulae to have taken place under 
circumstances which did not entirely exclude the action 
of the air, and consequent oxidation and removal of a 
certain quantity of hydrogen. Now the Laubacher coal 
28* 



330 CONVERSION OF WOOD 

is covered with a layer of basalt, and the coal of Ring- 
kuhl was taken from the lowest seam of layers, which 
possess a thickness of from 90 to 120 feet ; so that both 
may be considered as well protected from the air. 

During the formation of brown coal, the elements of 
carbonic acid have been separated from the wood either 
alone, or at the same time with a certain quantity of 
water. It is quite possible that the difference in the pro- 
cess of decomposition may depend upon the high tem- 
perature and pressure under which the decomposition 
took place. At least, a piece of wood assumed the 
character and appearance of Laubacher coal, after being 
kept for several weeks in the boiler of a steam-engine, 
and had then precisely the same composition. The 
change in this case was effected in water, at a tempera- 
ture of from 334° to 352° F. (150°— 160° C), and 
under a corresponding pressure. The ashes of the wood 
amounted to 0,51 per cent. ; a little less, therefore, than 
those of the Laubacher coal ; but this must be ascribed 
to the peculiar circumstances under which it was formed. 
The ashes of plants examined by Berthier amounted 
always to much more than this. 

The peculiar process by which the decomposition of 
these extinct vegetables has been effected, namely, a dis- 
engagement of carbonic acid from their substance, ap- 
pears still to go on at great depths in all the layers of 
wood-coal. At all events it is remarkable that springs 
impregnated with carbonic acid occur in many places, in 
the country between Meissner, in the electorate of Hesse, 
and the Eifel, which are known to possess large layers of 
wood-coal. These springs of mineral water are pro- 
duced on the spot at which they are found ; the springs 
;of common water meeting with carbonic acid during 
Iheir ascent, and becoming impregnated with it. 



INTO BROWN OR WOOD COAL. 331 

In the vicinity of the layers of wood-coal at Salzhau- 
sen (Hesse Darmstadt) an excellent acidulous spring 
of this kind existed a few years ago, and supplied all 
the inhabitants of that district ; but it was considered 
advantageous to surround the sides of the spring with 
sandstone, and the consequence was, that all the outlets 
to the carbonic acid were closed, for this gas generally 
gains access to the water from the sides of the spring. 
From that time to the present this valuable mineral 
water has disappeared, and in its place is found a spring 
of common water. 

Springs of water impregnated with carbonic acid 
occur at Schvvalheim, at a very short distance from the 
layers of wood coal at Dorheim. M. Wilhehni ob- 
served some time since, that they are formed of com- 
mon spring water which ascends from below, and of 
carbonic acid which issues from the sides of the spring. 
The same fact has been shown to be the case in the 
famed Fachinger spring, by M. Schapper. 

The carbonic acid gas from the springs in the Eifel 
is, according to Bischof^ seldom mixed with nitrogen 
or oxygen, and is probably produced in a manner simi- 
lar to that just described. At any rate the air does not 
appear to take any part in the formation of these acidu- 
lous springs. Their carbonic acid has evidently not 
been formed either by a combustion at high or low 
temperatures ; for if it were so, the gas resulting from 
the combustion would necessarily be mixed with | of 
nitrogen, but it does not conlain a trace of this ele- 
ment. The bubbles of gas which escape from these 
springs are absorbed by caustic potash, with the excep- 
tion of a residuum too small to be appreciated. 

The wood-coal of Dorheim and Salzhausen must have 



632 CONVERSION OF WOOD 

been formed in the same way as that of the neighbour- 
ing village of Laubach ; and since the latter contains 
the exact elements of woody fibre, minus a certain 
quantity of carbonic acid, its composition indicates very 
plainly the manner in which it has been produced. 

The coal of the upper bed is subjected to an inces- 
sant decay by the action of the air, by means of which 
its hydrogen is removed in the same manner as in the 
decay of wood. This is recognised by the way in 
which it burns, and by the formation of carbonic acid in 
the mines. 

The gases which are formed in mines of wood-coal, 
and cause danger in their working, are not combustible 
or inflammable as in mines of mineral coal ; but they 
consist generally of carbonic acid gas, and are very sel- 
dom intermixed with combustible gases. 

Wood-coal from the middle bed of the strata at 
Ringkuhl gave on analysis 65.40 — 64.01 carbon and 
4.75 — 4.76 * hydrogen ; the proportion of carbon 
here is the same as in specimens procured from greater 
depths, but that of the hydrogen is much less. 

Wood and mineral coal are always accompanied by 
iron pyrites (sulphuret of iron) or zinc blende (sulphu- 
ret of zinc) ; which minerals are still formed from salts 
of sulphuric acid, with iron or zinc, during the putre- 
faction of all vegetable matter. It is possible that ihe 
oxygen of the sulphates in the layers of wood-coal is 
the means by which the removal of the hydrogen is 
effected, since wood-coal contains less of this element 
than wood. 

* The analysis of brown coal from Ringkuhl, as well as all the analy- 
ses of the same substance given in this work, have been executed in 
this laboratory by M. Kiihncrt of Cassel. — L. 



INTO MINERAL COAL. 333 

According to the analysis of Richardson and Rcg- 
nault, the composition of the combustible materials in 
splint coal from Newcastle, and cannel coal from Lan- 
cashire, is expressed by the formula C24H13 0. 
When this is compared with the composition of woody 
fibre, it appears that these coals are formed from its 
elements, by the removal of a certain quantity of carbu- 
retted hydrogen and carbonic acid in the form of com- 
bustible oils. The composition of both of these coals 
is obtained by the subtraction of 3 atoms of carburetted 
hydrogen, 3 atoms of water, and 9 atoms of carbonic 
acid from, the formula of wood. 



3 atoms of carburetted hydrogen, C 3 H 6 
3 atoms of water, . . . H 3 O 3 
9 atoms of carbonic acid, . C 9 O 18 



C 36 H 22 022 = wood 
C12H9 02I 



Mineral coal, C 24 H 13 O 
Carburetted hydrogen generally accompanies all min- 
eral coal ; other varieties of coal contain volatile oils 
which may be separated by distillation with water. 
(Rcichenbach.) The origin of naptha is owing to a 
similar process of decomposition. Caking coal from 
Caresfield, near Newcastle, contains the elements of 
cannel coal, minus the constituents of olefiant gas C 4 
H4. 

The inflammable gases which stream out of clefts in 
the strata of mineral coal, or in rocks of the coal forma- 
tions, always contain carbonic acid, according to a 
recent examination by Bischnff, and also carburetted 
hydrogen, nitrogen, and olefiant gas ; the last of which 
had not been observed, until its existence in these gases 
was pointed out by Bischoff. The analysis of Jire- 
damp after it had been treated with caustic potash 
showed its constituents to be, 



334 rORMATION OF COAL. 



Gas from an 


Gerhard's pas- 


Gas from a 


al)amloneJ 


sage near Lu- 


mine near 


mine near 


isenlbal. 


Liekwege. 


Wallesweiler. 






Vol. 


Vol. 


Vol. 


n, 97 36 


83.08 


89.10 


G.32 


1.08 


16.11 


2.32 


14.94 


4.79 



Olefiant gas, 
Nitrogen gas, 

100.00 100.00 100 00 

The evolution of these gases proves that changes are 
constantly proceeding in the coal. 

It is obvious from this, that a continual removal of 
oxygen in the form of carbonic acid is effected from 
layers of wood-coal, in consequence of which the wood 
must approach gradually to the composition of mineral 
coal. Hydrogen, on the contrary, is disengaged from 
the constituents of mineral coal in the form of a com- 
pound of carbo-hydrogen ; a complete removal of all 
the hydrogen would convert coal into anthracite. 

The formula C 36 H 22 O 22, which is given for 
wood, has been chosen as the empirical expression of 
the analysis, for the purpose of bringing all the transfor- 
mations which woody fibre is capable of undergoing 
under one common point of view. 

Now, although the correctness of this formula must 
be doubted, until we know with certainty the true con- 
stitution of woody fibre, this cannot have the smallest 
influence on the account given of the changes to which 
woody fibre must necessarily be subjected in order to 
be converted into wood or mineral coal. The theo- 
retical expression refers to the quantity, the empirical 
merely to the relative propoition 'in which the elements 
of a body are united. Whatever form the first may 
assume, the empirical expression must always remain 
unchanged. 



POISONS, CONTAGIONS, MIASMS. 335 

CHAPTER XL 

ON POISONS, CONTAGIONS, AND MIASMS. 

A GREAT many chemical compounds, some derived 
from inorganic nature, and others formed in animals and 
plants, produce peculiar changes or diseases in the living 
animal organism. They destroy the vital functions of 
individual organs ; and when their action attains a certain 
degree of intensity, death is the consequence. 

The action of inorganic compounds, such as acids, al- 
kalies, metallic oxides, and salts, can in most cases be 
easily explained. They either destroy the continuity of 
particular organs, or they enter into combination with 
their substance. The action of sulphuric, muriatic, and 
oxalic acids, hydrate of potash, and all those substances 
which produce the direct destruction of the organs with 
which they come into contact, may be compared to a 
piece of iron, which can cause death by inflicting an in- 
jury on particular organs, either when heated to redness, 
or when in the form of a sharp knife. Such substances 
are not poisons in the limited sense of the word, for their 
injurious action depends merely upon their condition. 

The action of the proper inorganic poisons is owing, 
in most cases, to the formation of a chemical compound 
by the union of the poison with the constituents of the 
organ upon which it acts ; it is owing to an exercise of a 
chemical affinity more powerful than the vitality of the 
organ. 

It is well to consider the action of inorganic substan- 
ces in general, in order to obtain a clear conception of 
the mode of action of those which are poisonous. We 



336 POISONS, CONTAGIONS, MIASMS. 

find tliat certain soluble conripounds, when presented to 
difTerenl parts of tlie body, are absorbed by the blood, 
whence they are again eliniiiialed by the organs of secre- 
tion, either in a changed or in an uiiciianged state. 

Iodide of yotiiHsium^ sulpho-cyanurci of potassium, 
ferro-cyanuret of 'potassium, chlorate of potash, silicate 
of potash, and all salts with alkaline bases, when adtnin- 
islcred internally to man and animals in dilute solutions, 
or applied externally, may be agiin (lel(;cle(l in ihe blood, 
sweat, chyle, gall, and s|)jenic veins; but all of them are 
finally excreted from the body through the urinary pas- 
sages. 

Each of these substances, in its transit, produces a pe- 
culiar distiu'bance in the organism, — in other words, they 
exercise a rrjedicinal action upon it, but they themselves 
suffer no decomposition. If any of these substances en- 
ter into combination with any part of the body, the union 
cannot be of a j)ermanent kind ; for their reappearance 
in the urine shows that any compounds thus formed must 
have been again decomposed by the vital processes. 

Neutral citrates, acetates, and tartrates of the alkalies, 
suffer change in their passage through the organism. 
Their bases can indeed be detected in the urine, but the 
acids have entirely disappeared, and are replaced by car- 
bonic acid which has united with the bases. {(Jilbert 
Blane and WohJer.) 

The conversion of these salts of organic acids into car- 
bonates, indicates that a considerable quantity of oxygen 
must have united with their elements. In order to con- 
vert I eijuivalent of acetate of potash into the carbonate 
of the same base, 8 eijuivaletits of oxygen must combine 
with it, of which either 2 or 4 equivalents (according as 
an acid or neutral salt is produced) remain in combina- 



EFFECTS OF SALTS ON THK ORGANISM. 337 

tion with tlic alkali ; whilst the reinaininj; G or ^ equiva- 
lents are disenifaged as free carbonic acid. There is no 
evidence presented by the organism itself, to which these 
salts have been administered, that any of its ))r()|)cr con- 
stituents have yielded so great a quantity of oxygen as 
is necessary for tlu.'ir conversion into carbonates. 'J'heir 
oxidation can, therefore, only be ascrilied to the oxygen 
of the air. 

During the passage of these salts through the lungs, 
their acids take part in the peculiar process of erema- 
causis which proceeds in that organ ; a certain quantity 
of the oxygen gas inspired unites with their constituents, 
and converts their hydrogen into water, and their carbon 
into carbonic acid. J'art of this latter product (1 or 2 
equivalents) remains in combination with the alkaline 
base, forming a salt which suffers no further change by 
the process of oxidation ; and it is this salt which is sep- 
arated by the kidneys or liver. 

It is jnanifest, that the presence of these organic salts 
in the blood must |)roduce a change in the process of 
respiration. A part of the oxygen inspired, which usual- 
ly combines with the constituents of the blood, must^ 
when they are present, cotnbine with their acids, and 
thus be prevented from performing its usual oOice. 'J'he 
imtiK.'diale consequence of this must he the formation of 
arterial blood in less (|uantiiy, or in other words, iIk; pro- 
cess of respiration must be retarded. 

Neutral acetates, tartrates, and cilrales |)laced in con- 
tact with the air, and at the same time with animal or 
vegetable bodies in a state of eremacausis, produce ex- 
actly the same effects as we have described them to pro- 
duc;(.' iu the lungs. They participate in (he |)rocess of 
decay, and are converted into carbonates just as in the 
29 



338 POISONS, CONTAGIONS, MIASMS. 

living body. If impure solutions of these salts in water 
are left exposed to the air for any length of time, their 
acids are gradually decomposed, and at length entirely 
disappear. 

Free mineral acids, or organic acids which are not 
volatile, and salts of mineral acids with alkaline bases, 
completely arrest decay when added to decaying matter 
in sufficient quantity ; and when their quantity is small, 
the process of decay is protracted and retarded. They 
produce in living bodies the same phenomena as the neu- 
tral organic salts, but their action depends upon a differ- 
ent cause. 

The absorption by the blood of a quantity of an inor- 
ganic salt sufficient to arrest the process of eremacausis 
in the lungs, is prevented by a very remarkable property 
of all animal membranes, skin, cellular tissue, muscular 
fibre, &c. ; namely, by their incapability of being per- 
meated by concentrated saline solutions. It is only 
when these solutions are diluted to a certain degree with 
water that they are absorbed by animal tissues. 

A dry bladder remains more or less dry in saturated 
solutions of common salt, nitre, ferro-cyanuret of potas- 
sium, sulpho-cyanuret of potassium, sulphate of magne- 
sia, chloride of potassium, and sulphate of soda. These 
solutions run off its surface in the same manner as water 
runs from a plate of glass besmeared with tallow. 

Fresh flesh, over which salt has been strewed, is 
found after 24 hours' swimming in brine, although not a 
drop of water has been added. The water has been 
yielded by muscular fibre itself, and having dissolved the 
salt in immediate contact with it, and thereby lost the 
power of penetrating animal substances, it has on this 
account sej)arated from the flesh. The water still re- 



EFFECTS OF SALTS ON THE ORGANISM. 339 

tained by the flesh contains a proportionally small quan- 
tity of salt, having that degree of dilution at which a 
saline fluid is capable of penetrating animal substances. 

This property of animal tissues is taken advantage of 
in domestic economy, for the purpose of removing so 
much water from meat, that a sufficient quantity is not 
left to enable it to enter into putrefaction. 

In respect of this physical property of animal tissues, 
alcohol resembles the inorganic salts. It is incapable of 
moistening, that is, of penetrating animal substances, and 
possesses such an affinity for water as to extract it from 
moist substances. 

When a solution of a salt, in a certain degree of di- 
lution, is introduced into the stomach, it is absorbed ; 
but a concentrated saline solution, in place of being it- 
self absorbed, extracts water from the organ, and a vio- 
lent thirst ensues. Some interchange of water and salt 
takes place in the stomach : the coats of this viscus 
yield water to the solution, a part of which having pre- 
viously become sufficiently diluted is, on the other hand, 
absorbed. But the greater part of the concentrated so- 
lution of salt remains unabsorbed, and is not removed 
by the urinary passages ; it consequently enters the in- 
testines and intestinal canal, where it causes a dilution of 
the solid substance deposited there, and thus acts as a 
purgative. 

Each of the salts just mentioned possesses this purga- 
tive action, which depends on a physical property shared 
by all of them ; but besides this they exercise a medi- 
cinal action, because every part of the organism with 
which they come in contact absorbs a certain quantity of 
them. 

The composition of the salts has nothing to do with 



340 POISONS, CONTAGIONS, MIASMS. 

their purgative action ; it is quite a matter of indiffer- 
ence as far as the mere production of this action is con- 
cerned (not as to its intensity), whether the base be pot- 
ash or soda, or in many cases hme and magnesia ; and 
whether the acid be phosphoric, sulphuric, nitric, or hy- 
drochloric. 

Besides these salts, the action of which does not de- 
pend upon their power of entering into combination 
with the component parts of the organism ; there is a 
large class of others which, when introduced into the 
living body, effect changes of a very different kind, and 
produce diseases or death, according to the nature of 
these changes, without effecting a visible lesion of any 
organs. 

These are the true inorganic poisons, the action of 
which depends upon their power of forming permanent 
compounds with the substance of the membranes, and 
muscular fibre. 

Salts of lead, iron, bismuth, copper, and mercury, be- 
long to this class. 

When solutions of these salts are treated with a suffi- 
cient quantity of albumen, milk, muscular fibre, and an- 
imal membranes, they enter into combination with those 
substances, and lose their own solubility ; while the 
water in which they were dissolved loses all the salt 
which it contained. 

The salts of alkaline bases extract water from animal 
substances ; whilst the salts of the heavy metallic oxides 
are, on the contrary, extracted from the water, for they 
enter into combination with the animal matters. 

Now, when these substances are administered to an 
animal, they lose their solubility by entering into combi- 
nation with the membranes, cellular tissue, and muscular 



INORGANIC POISONS. 341 

fibre ; but in very few cases can they reach the blood. 
All experiments instituted for the purpose of determin- 
ing whether they pass into the urine have failed to detect 
them in that secretion. In fact, during their passage 
through the organism, they come into contact with many 
substances by which they are retained. 

The action of corrosive sublimate and arsenious acid 
is very remarkable in this respect. It is known that 
these substances possess, in an eminent degree, the 
property of entering into combination with all parts of 
animal and vegetable bodies, rendering them at the same 
time insusceptible of decay or putrefaction. Wood and 
cerebral substance are both bodies which undergo change 
with great rapidity and facility when subject to the influ- 
ence of air and water ; but if they are digested for some 
time with arsenious acid or corrosive sublimate, they 
may subsequently be exposed to all the influence of the 
atmosphere without altering in color or appearance. 

It is further known that those parts of a body, which 
come in contact with these substances during poisoning, 
and which therefore enter into combination with them, 
do not afterwards putrefy, so that there can be no doubt 
regarding the cause of their poisonous qualities. 

It is obvious that if arsenious acid and corrosive sub- 
limate are not prevented by the vital principle from en- 
tering into combination with the component parts of the 
body, and consequently from rendering them incapable 
of decay and putrefaction, they must deprive the organs 
of the principal property which appertains to their vital 
condition, viz. that of suffering and effecting transfor- 
mations ; or, in other words, organic life must be de- 
stroyed. If the poisoning is merely superficial, and the 
quantity of the poison so small that only individual parts 
29* 



342 POISONS, CONTAGIONS, MIASMS. 

of the body which are capable of being regenerated 
have entered into combination with it, then eschars are 
produced, — a phenomenon of a secondary kind, — the 
compounds of the dead tissues with the poison being 
thrown off by the healthy parts. From these considera- 
tions it may readily be inferred that all internal signs of 
poisoning are variable and uncertain ; for cases may 
happen, in which no apparent indication of change can 
be detected by simple observations of the parts, be- 
cause, as has been already remarked, death may occur 
without the destruction of any organs. 

When arsenious acid is administered in solution, it 
may enter into the blood. If a vein is exposed and 
surrounded with a solution of this acid, every blood- 
globule will combine with it, that is, will become poi- 
soned. 

The compounds of arsenic, which have not the 
property of entering into combination with the tissues 
of the organism, are without influence on life, even in 
large doses. Many insoluble basic salts of arsenious 
acid are known not to be poisonous. The substance 
called alkargen, discovered by Bunstn., which contains 
a very large quantity of arsenic, and approaches very 
closely in composition to the organic arsenious com- 
pounds found in the body, has not the slightest injurious 
action upon the organism. 

These considerations enable us to fix with tolerable 
certainty the limit at which the above substances cease 
to act as poisons. For since their combination with 
organic matters must be regulated by chemical laws, 
death will inevitably result, when the organ in contact 
with the poison finds sufficient of it to unite with atom 
for atom ; whilst if the poison is present in smaller 



INORGANIC POISONS. 343 

quantity, a part of the organ will retain its vital func- 
tions. 

According to the experiments of iV/w/f/er,* the equiv- 
alent in which fibrin combines with muriatic acid, and 
with the oxides of lead and copper, is expressed by the 
number 6361. It may be assumed therefore approxi- 
matively, that a quantity of fibrin corresponding to the 
number 6361 combines with 1 equivalent of arsenious 
acid, or 1 equivalent of corrosive sublimate. 

When 6361 parts of anhydrous fibrin are combined 
with 30,000 parts of water, it is in the state in which it 
is contained in muscular fibre or blood in the human 
body. 100 grains of fibrin in this condition would form 
a neutral compound of equal equivalents with 3^^ grains 
of arsenious acid, and 5 grains of corrosive sublimate. 

The atomic weight of the albumen of eggs and of 
the blood deduced from the analysis of the compound 
which it forms with oxide of silver is 7447, and that of 
aninial gelatin 5652. 

100 grains of albumen containing all the water with 
which it is combined in the living body, should conse- 
quently combine with 1| grain of arsenious acid. 

These proportions, which may be considered as the 
highest which can be adopted, indicate the remarkably 
high atomic weights of animal substances, and at the 
same time teach us what very small quantities of ar- 
senious acid or corrosive sublimate are requisite to pro- 
duce deadly effects. 

All substances administered as antidotes in cases of 
poisoning, act by destroying the power which arsenious 
acid and corrosive sublimate possess, of entering into 

* PoggendorfF's Annaien, Band xl. S. 259. 



344 POISONS, CONTAGIONS, MIASMS. 

combination with animal matters, and of thus acting as 
poisons. Unfortunately no other body surpasses them 
in that power, and the compounds which they forn) can 
only be broken up by affinities so energetic, that their 
action is as injurious as that of the above-named poisons 
themselves. The duty of the physician consists, there- 
fore, in his causing those parts of the poison which may 
be free and still uncombined, to enter into combination 
with some other body, so as to produce a compound in- 
capable of being decomposed or digested in the same 
conditions. Hydrated peroxide of iron is an invaluable 
substance for this purpose. 

When the action of arsenious acid or corrosive sub- 
limate is confined to the surface of an organ, those parts 
only are destroyed which enter into combination with 
it ; an eschar is formed which is gradually thrown off. 

Soluble salts of silver would be quite as deadly a 
poison as corrosive sublimate, did not a cause exist in 
the human body by which their action is prevented, un- 
less their quantity is very great. This cause is the 
presence of common salt in all animal liquids. Nitrate 
of silver, it is well known, combines with animal sub- 
stances, in the same manner as corrosive sublimate, and 
the compounds formed by both are exactly similar in 
the character of being incapable of decay or putrefac- 
tion. 

When nitrate of silver in a state of solution is applied 
to skin or muscular fibre, it combines with them instan- 
taneously ; animal substances dissolved in any liquid are 
precipitated by it, and rendered insoluble, or as it is 
usually termed, they are coagulated. The compounds 
thus formed are colorless, and so stable that they cannot 
be decomposed by other powerful chemical agents. 



ORGANIC POISONS. 345 

They are blackened by exposure to light, like all other 
compounds of silver, in consequence of a part of the 
oxide of silver which they contain being reduced to the 
metallic state. Parts of the body which have united with 
salts of silver, no longer belong to the living organism, 
for their vital functions have been arrested by combina- 
tion with oxide of silver ; and if they are capable of 
being reproduced, the neighbouring living structures 
throw them off in the form of an eschar. 

When nitrate of silver is introduced into the stomach, 
it meets with common salt and free muriatic acid ; and if 
its quantity is not too great, it is immediately converted 
into chloride of silver, — a substance which is absolutely 
insoluble in pure water. In a solution of salt or muriatic 
acid, however, chloride of silver does dissolve in ex- 
tremely minute quantity ; and it is this small part which 
exercises a medicinal influence when nitrate of silver is 
administered ; the remaining chloride of silver is elimin- 
ated from the body in the ordinary way. Solubility is 
necessary to give efficacy to any substance in the human 
body. 

The soluble salts of lead possess many properties in 
common with the salts of silver and mercury ; but all 
compounds of lead with organic matters are capable of 
decomposition by dilute sulphuric acid. The disease 
called painter's colic is unknown in all manufactories of 
white lead in which the workmen are accustomed to take 
as a preservative sulphuric acid lemonade (a solution of 
sugar rendered acid by sulphuric acid). 

The organic substances which have combined in the 
living body with metallic oxides or metallic salts, lose 
their property of imbibing water and retaining it, without 
at the same time being rendered incapable of permitting 



346 POISONS, CONTAGIONS, MIASMS. 

liquids to penetrate through their pores. A strong con- 
traction and shrinking of a surface is the general effect 
of contact with these metallic bodies. But corrosive 
sublimate, and several of the salts of lead, possess a pe- 
culiar property, in addition to those already mentioned. 
When they are present in excess, they dissolve the first 
formed insoluble compounds, and thus produce an effect 
quite the reverse of contraction, namely, a softening of 
the part of the body on which they have acted. 

Salts of oxide of copper, even when in combination 
with the most powerful acids, are reduced by many vege- 
table substances, particularly such as sugar and honey, 
either into metallic copper, or into the red suboxide, 
neither of which enters into combination with animal 
matter. It is well known that sugar has been long em- 
ployed as the most convenient antidote for poisoning by 
copper. 

With respect to some other poisons, namely, hydro- 
cyanic acid and the organic bases strychnia and brucia, 
we are acquainted with no facts calculated to elucidate 
the nature of their action. It may, however, be pre- 
sumed with much certainty, that experiments upon their 
mode of action on different animal substances, would 
very quickly lead to the most satisfactory conclusions, re- 
garding the cause of their poisonous effects. 

There is a peculiar class of substances, which are 
generated during certain processes of decomposition, and 
which act upon the animal economy as deadly poisons, 
not on account of their power of entering into combina- 
tion with it, or by reason of iheir containing a poisonous 
material, but solely by virtue of their peculiar condition. 

In order to attain to a clear conception of the mode of 
action of these bodies, it is necessary to call to mind the 



ORGANIC POISONS. 347 

cause on which we have shown the phenomena of fer- 
mentation, decay, and putrefaction to depend. 

This cause may be expressed by the following law, 
long since proposed by La Place and Berthollet, although 
its truth with respect to chemical phenomena has only 
lately been proved. ".^3 molecule set in motion by any 
power can impart its own motion to another molecule with 
which it may he in contact." 

This is a law of dynamics, the operation of which is 
manifest in all cases, in which the resistance (force, 
affinity, or cohesion) opposed to the motion is not suf- 
ficient to overcome it. 

We have seen that ferment or yeast is a body in the 
state of decomposition, the atoms of which, consequenlly, 
are in a state of motion or transposition. Yeast placed 
in contact with sugar, communicates to the elements of 
that compound the same state, in consequence of which, 
the constituents of the sugar arrange themselves into new 
and simpler forms, namely, into alcohol and carbonic 
acid. In these new compounds, the elements are united 
together by stronger affinities than they were in the sugar, 
and therefore under the conditions in which they were 
produced further decomposition is arrested. 

We know, also, that the elements of sugar assume 
totally different arrangements, when the substances which 
excite their transposition are in a different state of de- 
composition from the yeast just mentioned. Thus, when 
sugar is acted on by rennet or putrefying vegetable 
juices, it is not converted into alcohol and carbonic acid, 
but into lactic acid, mannite, and gum. 

Again, it has been shown, that yeast added to a solu- 
tion of pure sugar gradually disappears, but that when 
added to vegetable juices which contain gluten as well as 



348 POISONS, CONTAGIONS, MIASMS. 

sugar, it is reproduced by the decomposition of the for- 
mer substance. 

The yeast with which these liquids are made to fer- 
ment, has itself been originally produced from gluten. 

The conversion of gluten into yeast in these vegeta- 
ble juices is dependent on the decomposition (fermenta- 
tion) of sugar ; for, when the sugar has completely 
disappeared, any gluten which may still remain in the 
liquid, does not suffer change from contact with the 
newly-deposited yeast, but retains all the characters of 
gluten. 

Yeast is a product of the decomposition of gluten ; 
but it passes into a second stage of decomposition when 
in contact with water. On account of its being in this 
state of further change, yeast excites fermentation in a 
fresh solution of sugar, and if this second saccharine 
fluid should contain gluten, (should it be wort, for ex- 
ample,) yeast is again generated in consequence of the 
transposition of the elements of the sugar exciting a 
similar change in this gluten. 

After this explanation, the idea that yeast reproduces 
itself as seeds reproduce seeds, cannot for a moment be 
entertained. 

From the foregoing facts it follows, that a body in the 
act of decomposition (it may be named the exciter), 
added to a mixed fluid in which its constituents are con- 
tained, can reproduce itself in that fluid, exactly in the 
same manner as new yeast is produced when yeast is 
added to liquids containing gluten. This must be more 
certainly eflected when the liquid acted upon contains 
the body by the metamorphosis of which the exciter has 
been originally formed. 

It is also obvious, that if the exciter be able to impart 



PUTRID POISONS. 349 

its own state of transformation to one only of the com- 
ponent parts of the mixed hquid acted upon, its own re- 
production may be the consequence of the decomposi- 
tion of this one body. 

This law may be applied to organic substances form- 
ing part of the animal organism. We know that all the 
constituents of these substances are formed from the 
blood, and that the blood by its nature and constitution 
is one of the most complex of all existing matters. 

Nature has adapted the blood for the reproduction of 
every individual part of the organism ; its principal 
character consists in its component parts being subor- 
dinate to every attraction. These are in a perpetual 
state of change or transformation, which is efiected in 
the most various ways through the influence of the dif- 
ferent organs. 

The individual organs, such as the stomach, cause all 
the organic substances conveyed to them which are ca- 
pable of transformation to assume new forms. The 
stomach compels the elements of these substances to 
unite into a compound fitted for the formation of the 
blood. But the blood possesses no power of causing 
transformations ; on the contrary, its principal character 
consists in its readily suffering transformations ; and no 
other matter can be compared in this respect with it. 

Now it is a well-known fact, that when blood, cere- 
bral substance, gall, pus, and other substances in a state 
of putrefaction, are laid upon fresh wounds ; vomiting, 
debility, and at length death, are occasioned. It is also 
well known that bodies in anatomical rooms frequently 
pass into a state of decomposition which is capable of 
imparting itself to the hving body, the smallest cut with 
30 



350 POISONS, CONTAGIONS, MIASMS. 

a knife which has been used in their dissection producing 
in these cases dangerous consequences. 

The poison of bad sausages belongs to this class of 
noxious substances. 

Several hundred cases are known in which death has 
occurred from the use of this kind of food. 

In Wiirtemburg especially, these cases are very fre- 
quent, for there the sausages are prepared from very va- 
rious materials. 

Blood, liver, bacon, brains, milk, meal, and bread, 
are mixed together with salt and spices ; the mixture is 
then put into bladders or intestines, and after being 
boiled is smoked. 

When these sausages are well prepared, they may be 
preserved for months, and furnish a nourishing, savoury 
food ; but when the spices and salt are deficient, and 
particularly when they are smoked too late or not suffi- 
ciently, they undergo a peculiar kind of putrefaction 
which begins at the centre of the sausage. Without 
any appreciable escape of gas taking place, they become 
paler in color, and more soft and greasy in those parts 
which have undergone putrefaction, and they are found 
to contain free lactic acid or lactate of ammonia ; pro- 
ducts which are universally formed during the putrefac- 
tion of animal and vegetable matters. 

The cause of the poisonous nature of these sausages 
was ascribed at first to hydrocyanic acid, and afterwards 
to sebacic acid, although neither of these substances had 
been detected in them. But sebacic acid is no more 
poisonous than benzoic acid, with which it has so many 
properties ia common ; and the symptoms produced 
are sufficient to show, that hydrocyanic acid is not the 
poison. 



PUTRID POISONS. 351 

The death which is the consequence of poisoning by 
putrefied sausages succeeds very hngering and remarka- 
ble symptoms. There is a gradual wasting of muscular 
fibre, and of all the constituents of the body similarly 
composed ; the patient becomes much emaciated, dries 
to a complete mummy and finally dies. The carcase is 
stiff, as if frozen, and is not subject to putrefaction. 
During the progress of the disease the saliva becomes 
viscous and acquires an offensive smell. 

Experiments have been made for the purpose of as- 
certaining the presence of some matter in the sausages 
to which their poisonous action could be ascribed ; 
but no such matter has been detected. Boiling water 
and alcohol completely destroy the poisonous properties 
of the sausages, without themselves acquiring similar 
properties. 

Now this is the peculiar character of all substances 
which exert an action by virtue of their existing condi- 
tion, — of those bodies the elements of which are in the 
state of decomposition or transposition ; a state which is 
destroyed by boiling water and alcohol without the cause 
of the influence being imparted to those liquids ; for a 
state of action or power cannot be preserved in a liquid. 

Sausages, in the state here described, exercise an ac- 
tion upon the organism, in consequence of the stomach 
and other parts with which they come in contact not hav- 
ing the power to arrest their decomposition ; and entering 
the blood in some way or other, while still possessing 
their whole power, they impart their peculiar action to 
the constituents of that fluid. 

The poisonous properties of decayed sausages are not 
destroyed by the stomach as those of the smallpox virus 
are. All the substances in the body capable of putre- 



352 POISONS, CONTAGIONS, MIASMS. 

faction, are gradually decomposed during the course of 
the disease, and after death nothing remains except fat, 
tendons, bones, and a few other substances, which are in- 
capable of putrefying in the conditions afforded by the 
body. 

Jt is impossible to mistake the modus operandi of this 
poison, for Colin has clearly proved, that muscle, urine, 
cheese, cerebral substance, and other matters, in a state 
of putrefaction, communicate their own state of decom- 
position to substances much less prone to change of com- 
position than the blood. When placed in contact with 
a solution of sugar, they cause its putrefaction, or the 
transposition of its elements into carbonic acid and al- 
cohol. 

When putrefying muscle or pus Is placed upon a fresh 
wound, it occasions disease and death. It is obvious, that 
these substances communicate their own state of putre- 
faction to the sound blood from which they were pro- 
duced, exactly in the same manner as gluten in a state 
of decay or putrefaction causes a similar transformation 
in a solution of sugar- 
Poisons of this kind are even generated by the body 
itself in particular diseases. In smallpox, plague, and 
syphilis, substances of a peculiar nature are formed from 
the constituents of the blood. These matters are capa- 
ble of inducing in the blood of a healthy individual a 
decomposition similar to that of which they themselves 
are the subjects ; in other words, they produce the same 
disease. The morbid virus appears to reproduce itself 
just as seeds appear to reproduce seeds. 

The mode of action of a morbid virus exhibits such a 
strong similarity to the action of yeast upon liquids con- 
taining sugar and gluten, that the two processes have 



MORBID POISONS. 353 

been long since compared to one another, although mere- 
ly for the purpose of illustration. But when the phe- 
nomena attending the action of each respectively are con- 
sidered more closely, it will in reality be seen that their 
influence depends upon the same cause. 

In dry air, and in the absence of moisture, all these 
poisons remain for a long time unchanged ; but when 
exposed to the air in the moist condition, they lose very 
rapidly their peculiar properties. In the former case^, 
those conditions are afforded which arrest their decom- 
position without destroying it ; in the latter, all the cir- 
cumstances necessary for the completion of their decom- 
position are presented. 

The temperature at which water hoils^ and contact 
tvith alcohol, render such poisons inert. Acids., salts of 
mercury, sulphurous acid, chlorine, iodine, bromine, 
aromatic substances, volatile oils, and particularly empy- 
reumatic oils, smoke, and a decoction of coffee, com- 
pletely destroy their contagious properties, in some cases 
combining with them or otherwise effecting their decom- 
position. Now all these agents, without exception, retard 
fermentation, putrefaction, and decay, and when present 
in sufficient quantity, completely arrest these processes 
of decomposition. 

A peculiar matter to which the poisonous action is 
due, cannot, we have seen, be extracted from decayed 
sausages; and it is equally impossible to obtain such a 
principle from the virus of smallpox or plague, and for 
this reason, that their peculiar power is due to an active 
condition recognisable by our senses, only through the 
phenomena which it produces. 

In order to explain the effects of contagious matters, 
a peculiar principle of life has been ascribed to them, — 
30* 



354 POISONS, CONTAGIONS, MIASMS. 

a life similar to that possessed by the germ of a seed, 
wiiich enables it under favorable conditions to develope 
and multiply itself. It would be impossible to find a 
more correct figurative representation of these phenom- 
ena; it is one which is applicable to contagions, as well 
as to ferment, to animal and vegetable substances, in a 
state of fermentation, putrefaction, or decay, and even to 
a piece of decaying wood, which, by mere contact with 
fresh wood, causes the latter to undergo gradually the 
same change, and become decayed and mouldered. 

If the property possessed by a body of producing such 
a change in any other substance as causes the reproduc- 
tion of itself, with all its properties, be regarded as life, 
then, indeed, all the above phenomena may be ascribed 
to life. But in that case they must not be considered 
as the only processes due to vitality, for the above inter- 
pretation of the expression embraces the majority of the 
phenomena which occur in organic chemistry. Life 
would, according to that view, be admitted to exist in 
every body in which chemical forces act. 

If a body A, for example, oxamide (a substance scarce- 
ly soluble in water, and without the slightest taste), be 
brought into contact with another compound B, which is 
to be reproduced ; and if this second body be oxalic acid 
dissolved in water, then the following changes are ob- 
served to take place: — The oxamide is decomposed 
by the oxalic acid, provided the conditions necessary for 
their exercising an action upon one another are present. 
The elements of water unite with the constituents of oxa- 
mide, and ammonia is one product formed, and oxalic 
acid the other, both in exactly the proper proportions to 
combine and form a neutral salt. 

Here the contact of oxamide and oxalic acid induces 



MORBID POISONS. 355 

a transformation of the oxamide, which is decomposed 
into oxalic acid and ammonia. The oxalic acid thus 
formed as well as that originally added, are shared by 
the ammonia, — or in other words, as much free oxalic 
acid exists after the decomposition as before it, and is 
of course still possessed of its original power. It mat- 
ters not whether the free oxalic acid is that originally 
added, or that newly produced ; it is certain that it has 
been reproduced in an equal quantity by the decompo- 
sition. 

If we now add to the same mixture a fresh portion of 
oxamide, exactly equal in quantity to that first used, and 
treat it in the same manner, the same decomposition is 
repeated ; the free oxalic acid enters into combination, 
whilst another portion is liberated. In this manner a 
very minute quantity of oxalic acid may be made to 
effect the decomposition of several hundred pounds of 
oxamide ; and one grain of the acid to reproduce itself 
in unlimited quantity. 

We know that the contact of the virus of smallpox 
causes such a change in the blood, as gives rise to the 
reproduction of the poison from the constituents of the 
fluid. This transformation is not arrested until all the 
particles of the blood which are susceptible of the de- 
composition have undergone the metamorphosis. We 
have just seen that the contact of oxalic acid with oxa- 
mide caused the production of fresh oxalic acid, which 
in its turn exercised the same action on a new portion 
of oxamide. The transformation was only arrested in 
consequence of the quantity of oxamide present being 
limited. In their form both these transformations be- 
long to the same class. But no one but a person quite 
unaccustomed to view such changes will ascribe them 



356 POISONS, CONTAGIO]\S, MIASMS. 

to a vital power, although we admit they correspond re- 
markably to our common conceptions of life ; they are 
really chemical processes dependent upon the common 
chemical forces. 

Our notion of life involves something more than mere 
reproduction, namely, the idea of an active power exer- 
cised by virtue of a definite form, and production and 
generation i7i a definite form. By chemical agency we 
can produce the constituents of muscular fibre, skin, and 
hair ; but we can form by their means no organized tis- 
sue, no organic cell. 

The production of organs, the cooperation of a sys- 
tem of organs, and their power not only to produce 
their component parts from the food presented to them, 
but to generate themselves in their original form and with 
all their properties, are characters belonging exclusively 
to organic life ; and constitute a form of reproduction 
independent of chemical powers. 

The chemical forces are subject to the invisible cause 
by which this form is produced. Of the existence of 
this cause itself we are made aware only by the phenom- 
ena which it produces. Its laws must be investigated 
just as we investigate those of the other powers which 
effect motion and changes in matter. 

The chemical forces are subordinate to this cause of 
life, just as they are to electricity, heat, mechanical mo- 
tion and friction. By the influence of the latter forces, 
they suffer changes in their direction, an increase or 
dimunition of their intensity, or a complete cessation or 
reversal of their action. 

Such an influence and no other is exercised by the 
vital principle over the chemical forces ; but in every 



THEIR MODE OF ACTION. 357 

case where combination or decomposition takes place, 
chemical affinity and cohesion are in action. 

The vital principle is only known to us through the 
peculiar form of its instruments, that is, through the or- 
gans in which it resides. Hence, whatever kind of en- 
ergy a substance may possess, if it is amorphous and 
destitute of organs from which the impulse, motion, or 
change proceeds, it does not live. Its energy depends 
in this case on a chemical action. -Light, heat, electrici- 
ty, or other influences may increase, diminish, or ar- 
rest this action, but they are not its efficient cause. 

In the same way the vital principle governs the chem- 
ical powers in the living body. All those substances to 
which we apply the general name of food, and all the 
bodies formed from them in the organism, are chemical 
compounds. The vital principle has, therefore, no 
Olhfer resistance to overcome, '" order to convert these 
substances into component parts of the organism, than 
the chemical powers by which their constituents are 
held together. If the food possessed life, not merely 
the chemical forces, but this vitality, would offev resist- 
ance to the vital force of the organism it nourished. 

All substances adapted for assimilation are bodies of 
a very complex constitution, their atoms are highly com- 
plex, and are held together only by a weak chemical 
action. They are formed by the union of two or more 
simpler compounds ; and in proportion as the number 
of their atoms augments, their disposition to enter into 
new combination is diminished ; that is, they lose the 
power of acting chemically upon other bodies. 

Their complex nature, however, renders them more 
liable to be changed, by the agency of external causes, 
and thus to suffer decomposition. Any external agen- 



358 POISONS, CONTAGIONS, MIASMS. 

cy, in many cases even mechanical friction, is sufficient 
to cause a disturbance in the equilibrium of the attrac- 
tion of their constituents ; they arrange themselves 
either into new, more simple, and permanent combina- 
tions, or, if a foreign attraction exercise its influence 
upon them, they arrange themselves in accordance with 
that attraction. 

The special characters of food, that is of substances 
fitted for assimilation, are absence of active chemical 
properties, and the capability of yielding to transforma- 
tions. 

The equilibrium in the chemical attractions of the 
constituents of the food is disturbed by the vital princi- 
ple, as we know it may be by many other causes. But 
the union of its elements, so as to produce new combi- 
nations and forms, indicates the presence of a peculiar 
mode of attraction, and the existence of a power dis- 
tinct from all other powers of nature, namely, the vitjil 
principle. 

All bodies of simple composition possess a greater 
or less disposition to form combinations. Thus oxaHc 
acid is one of the simplest of the organic acids, while 
stearic acid is one of the most complex ; and the former 
is the strongest, the latter one of the weakest in respect 
to active chemical character. By virtue of this dispo- 
sition, simple compounds produce changes in every 
body which offers no resistance to their action ; they 
enter into combination and cause decomposition. 

The vital principle opposes to the continual action 
of the atmosphere, moisture and temperature upon the 
organism, a resistance which is, in a certain degree, 
invincible. It is by the constant neutralization and re- 



THEIR MODE OF ACTION. 359 

newal of these external influences that life and motion 
are maintained. 

The greatest wonder in the living organism is the 
fact, that an unfathomable wisdom has made the cause 
of a continual decomposition or destruction, namely, 
the support of the process of respiration, to be the 
means of renewing the organism, and of resisting all the 
other atmospheric influences, such as those of moisture 
and changes of temperature. 

When a chemical compound of simple constitution 
is introduced into the stomach, or any other part of the 
organism, it must exercise a chemical action upon all 
substances with which it comes in contact ; for we 
know the pecuhar character of such a body to be an 
aptitude and power to enter into combinations and 
effect decompositions. 

The chemical action of such a compound is of course 
opposed by the vital principle. The results produced 
depend upon the strength of their respective actions ; 
either an equilibrium of both powers is attained, a 
change being effected without the destruction of the 
vital principle, in which case a medicinal effect is occa- 
sioned ; or the acting body yields to the superior force 
of vitality, that is, it is digested; or lastly, the chemical 
action obtains the ascendency and acts as a poison. 

Every substance may be considered as nutriment^ 
which loses its former properties when acted on by the 
vital principle, and does not exercise a chemical action 
upon the living organ. 

Another class of bodies change the direction, the 
strength, and intensity of the resisting force (the vital 
principle), and thus exert a modifying influence upon 
the functions of its organs. They produce a disturbance 



360 POISONS, CONTAGIONS, MIASMS. 

in the system, either by their presence, or by them- 
selves undergoing a change ; these are medicaments. 

A third class of compounds are called poisons, when 
they possess the property of uniting with organs or with 
their component parts, and when their power of effect- 
ing this is stronger than the resistance offered by the 
vital principle. 

The quantity of a substance and its condition must, 
obviously, completely change the mode of its chemical 
action. 

Increase of quantity is known to be equivalent to 
superior affinity. Hence a medicine administered in 
excessive quantity may act as a poison, and a poison in 
small doses as a medicine. 

Food will act as a poison, that is, it will produce 
disease, when it is able to exercise a chemical action 
by virtue of its quantity ; or, when either its condition 
or its presence retards, prevents, or arrests the motion 
of any organ. 

A compound acts as a poison when all the parts of 
an organ with which it is brought into contact enter into 
chemical combination with it, while it may operate as a 
medicine, when it produces only a partial change. 

jNo other component part of the organism can be 
compared to the blood, in respect of the feeble resist- 
ance which it offers to exterior influences. The blood 
is not an organ which is formed, but an organ in the act 
of formation ; indeed, it is the sum of all the organs 
which are being formed. The chemical force and the 
vital principle hold each other in such perfect equilib- 
rium, that every disturbance, however trifling, or from 
whatever cause it may proceed, effects a change in the 
blood. This liquid possesses so little of permanence, 



THEIR MODE OF ACTION. 361 

that it cannot be removed from the body without imme- 
diately suffering a change, and cannot come in contact 
with any organ in the body, without yielding to its 
attraction. 

The slightest action of a chemical agent upon the 
blood exercises an injurious influence ; even the mo- 
mentary contact with the air in the lungs, although 
effected through the medium of cells and membranes, 
alters the color and other qualities of the blood. Ev- 
ery chemical action propagates itself through the mass of 
the blood ; for example, the active chemical condition 
of the constituents of a body undergoing decomposition, 
fermentation, putrefaction, or decay, disturbs the equilib- 
rium between the chemical force and the vital prin- 
ciple in the circulating fluid. The former obtains the 
preponderance. Numerous modifications in the com- 
position and condition of the compounds produced from 
the elements of the blood, result from the conflict of the 
vital force with the chemical affinity, in their incessant 
endeavour to overcome one another. 

All the characters of the phenomena of contagion 
tend to disprove the existence of life in the contagious 
matters. They without doubt exercise an influence 
very similar to some processes in the living organism ; 
but the cause of this influence is chemical action, which 
is capable of being subdued by other chemical actions, 
by opposed agencies. 

Several of the poisons generated in the body by dis- 
ease lose all their power when introduced into the stom- 
ach, but others are not thus destroyed. 

It is a fact very decisive of their chemical nature and 
mode of action, that those poisons which are neutral or 
alkaline, such as the poisonous matter of the contagious 
31 



362 POISONS, CONTAGIONS, MIASMS. 

fever in cattle, {typhus coniagiosus ruminantium^) or 
that of the smallpox, lose their whole power of conta- 
gion in the stomach ; whilst that of sausages, which has 
an acid reaction, retains all its frightful properties under 
the same circumstances. 

In the former of these cases, the free acid present 
in the stomach destroys the action of the poison, the 
chemical properties of which are opposed to it ; whilst 
in the latter it strengthens, or at all events does not offer 
any impediment to poisonous action. 

Microscopical examination has detected peculiar 
bodies resembling the globules of the blood in malig- 
nant putrefying pus, in the matter of vaccine, &c. 
The presence of these bodies has given weight to the 
opinion, that contagion proceeds from the development 
of a diseased organic life ; and these formations have 
been regarded as the living seeds of disease. 

This view, which is not capable of discussion, has led 
those philosophers who are accustomed to search for 
explanations of phenomena in forms, to consider the 
yeast produced by the fermentation of beer as possessed 
of life. They have imagined it to be composed of ani- 
mals or plants, which nourish themselves from the sugar 
in which they are placed, and at the same time yield al- 
cohol and carbonic acid as excrementitious matters. * 

It would perhaps appear wonderful if bodies, possess- 
ing a crystalline structure and geometrical figure, were 
formed during the processes of fermentation and putre- 
faction from the organic substances and tissues of or- 
gans. We know, on the contrary, that the complete 
dissolution into inorganic compounds is preceded by a 

*JnnaJen der Pharmacie, Band xxix. S. 93 und 100. 



THEIR MODE OF ACTION. 363 

series of transformations, in which the organic struc- 
tures gradually resign their forms. 

Blood, in a state of decomposition, may appear to 
the eye unchanged ; and, when we recognise the globules 
of blood in a liquid contagious matter, the utmost that 
we can thence infer is, that those globules have taken no 
part in the process of decomposition. All the phos- 
phate of lime may be removed from bones, leaving them 
transparent and flexible like leather, without the form of 
the bones being in the smallest degree lost. Again, 
bones may be burned until they be quite white, and con- 
sist merely of a skeleton of phosphate of lime, but they 
will still possess their original form. In the same way 
processes of decomposition in the blood may affect in- 
dividual constituents only of that fluid, which will be- 
come destroyed and disappear, whilst its other parts will 
maintain the original form. 

Several kinds of contagion are propagated through 
the air : so that, according to the view already men- 
tioned, we must ascribe life to a gas, that is, to an aeri- 
form body. 

All the supposed proofs of the vitality of contagions 
are merely ideas and figurative representations, fitted to 
render the phenomena more easy of apprehension by 
our senses, without explaining them. These figurative 
expressions, with which we are so willingly and easily 
satisfied in all sciences, are the foes of all inquiries into 
the mysteries of nature ; they are like [he fata morgana, 
which show us deceitful views of seas, fertile fields, and 
luscious fruits, but leave us languishing when we have 
most need of what they promise. 

It is certain that the action of contagions is the result 
of a peculiar influence dependent on chemical forces, 



364 POISONS, CONTAGIONS, MIASMS. 

and in no way connected with the vital principle. This 
influence is destroyed by chemical actions, and mani- 
fests itself wherever it is not subdued by some antago- 
nist power. Its existence is recognised in a connected 
series of changes and transformations, in which it causes 
all substances capable of undergoing similar changes to 
participate. 

An animal substance in the act of decomposition, or 
a substance generated from the component parts of a 
living body by disease, communicates its own condition 
to all parts of the system capable of entering into the 
same state, if no cause exist in these parts by which the 
change is counteracted or destroyed. 

Disease is excited by contagion. 

The transformations produced by the disease assume 
a series of forms. 

In order to obtain a clear conception of these trans- 
formations, we may consider the changes which substan- 
ces, more simply composed than the living body, suffer 
from the influence of similar causes. When putrefying 
blood or yeast in the act of transformation is placed in 
contact with a solution of sugar, the elements of the 
latter substance are transposed, so as to form alcohol 
and carbonic acid. 

A piece of the rennet-stomach of a calf in a state of 
decomposition occasions the elements of sugar to as- 
sume a different arrangement. The sugar is converted 
into lactic acid without the addition or loss of any ele- 
ment. (1 atom of sugar of grapes C12 Hl2 012 
yields two atoms of lactic acid =2 (C6 H6 06.) 

When the juice of onions, or of beet-root, is made to 
ferment at high temperatures, lactic acid, mannite, and 
gum are formed. Thus, according to the different states 



THEIR MODE OF ACTION. 365 

of the transposition of the elements of the exciting body, 
the elements of the sugar arrange themselves in differ- 
ent manners, that is, different products are formed. 

The immediate contact of the decomposing substance 
with the sugar, is the cause by which its particles are 
made to assume new forms and natures. The removal 
of that substance occasions the cessation of the decom- 
position of the sugar, so that should its transformation 
be completed before the sugar, the latter can suffer no 
further change. 

In none of these processes of decomposition is the 
exciting body reproduced ; for the conditions necessary 
to its reproduction do not exist in the elements of the 
sugar. 

Just as yeast, putrefying flesh, and the stomach of a 
calf, in a state of decomposition, when introduced into 
solutions of sugar, effect the transformation of this sub- 
stance, without being themselves regenerated ; in the 
same manner, miasms and certain contagious matters 
produce diseases in the human organism, by communi- 
cating the state of decomposition, of which they them- 
selves are the subject, to certain parts of the organism, 
without themselves being reproduced in their peculiar 
form and nature during the progress of the decomposi- 
tion. 

The disease in this case is not contagious. 

Now, when yeast is introduced into a mixed liquid 
containing both sugar and gluten, such as wort, the act 
of decomposition of the sugar effects a change in the 
form and nature of the gluten, which is, in consequence, 
also subjected to transformation. As long as some of 
the fermenting sugar remains, gluten continues to be 
separated as yeast, and this new matter in its turn ex- 
31 * 



366 POISONS, CONTAGIONS, MIASMS. 

cites fermentation in a fresh solution of sugar or wort. 
If tiie sugar, however, should be first decomposed, the 
gluten which remains in solution is not converted into 
yeast. We see, therefore, that the reproduction of the 
exciting body here depends, — 

1. Upon the presence of that substance from which 
it was originally formed. 

2. Upon the presence of a compound which is capa- 
ble of being decomposed by contact with the exciting 
body. 

If we express in the same terms the reproduction of 
contagious matter in contagious diseases, since it is quite 
certain that they must have their origin in the blood, we 
must admit that the blood of a healthy individual contains 
substances, by the decomposition of which the exciting 
body or contagion can be produced. It must further 
be admitted, when contagion results, that the blood con- 
tains a second constituent, capable of being decomposed 
by the exciting body. It is only in consequence of the 
conversion of the second constituent, that the original 
exciting body can be reproduced. 

A susceptibility of contagion indicates the presence 
of a certain quantity of this second body in the blood of 
a healthy individual. The susceptibility for the disease 
and its intensity must augnient according to the quantity 
of that body present in the blood ; and in proportion to 
its diminution or disappearance, the course of the dis- 
ease will change. 

When a quantity, however small, of contagious mat- 
ter, that is of the exciting body, is introduced into the 
blood of a healthy individual, it will be again generated 
in the blood, just as yeast is reproduced from wort. Its 
condition of transformation will be communicated to a 



THEIR MODE OF ACTION. 367 

constituent of the blood ; and in consequence of the 
transformation suffered by this substance, a body identi- 
cal with or similar to the exciting or contagious matter 
will be produced from another constituent substance of 
the blood. The quantity of the exciting body newly 
produced must constantly augment, if its further trans- 
formation or decomposition proceeds more slowly than 
that of the compound in the blood, the decomposition of 
which it effects. 

If the transformation of the yeast generated in the 
fermentation of wort proceeded with the same rapidity 
as that of the particles of the sugar contained in it, both 
would simultaneously disappear when the fermentation 
was completed. But yeast requires a much longer time 
for decomposition than sugar, so that after the latter has 
completely disappeared, there remains a much larger 
quantity of yeast than existed in the fluid at the com- 
mencement of the fermentation, — yeast which is still 
in a state of incessant progressive transformation, and 
therefore possessed of its peculiar property. 

The state of change or decomposition which affects 
one particle of blood, is imparted to a second, a third, 
and at last to all the particles of blood in the whole 
body. It is communicated in like manner to the blood 
of another individual, to that of a third person, and so 
on, — or in other words, the disease is excited in them 
also. 

It is quite certain that a number of peculiar substances 
exist in the blood of some men and animals, which are 
absent from the blood of others. 

The blood of the same individual contains, in child- 
hood and youth, variable quantities of substances, which 
are absent from it in other stages of growth. The sus- 



368 POISONS, CONTAGIONS, MIASMS. 

ceptibility of contagion by peculiar exciting bodies in 
childhood, indicates a propagation and regeneration of 
the exciting bodies, in consequence of the transformation 
of certain substances which are present in the blood, and 
in the absence of which no contagion could ensue. The 
form of a disease is termed benignant^ when the trans- 
formations are perfected on constituents of the body 
which are not essential to life, without the other parts 
taking a share in the decomposition ; it is termed malig- 
nant when they affect essential organs. 

It cannot be supposed that the different changes in the 
blood, by which its constituents are converted into fat, 
muscular fibre, substance of the brain and nerves, bones, 
hair, »&.c., and the transformation of food into blood, can 
take place without the simultaneous formation of new 
compounds, which require to be removed from the body 
by the organs of excretion. 

In an adult these excretions do not vary much either 
in their nature or quantity. The food taken is not em- 
ployed in increasing the size of the body, but merely for 
the purpose of replacing any substances which may be 
consumed by the various actions in the organism ; every 
motion, every manifestation of organic properties, and 
every organic action being attended by a change in the 
material of the body, and by the assumption of a new 
form by its constituents.* 

But in a child this normal condition of sustenance is 



* The experiments of Barruel upon the different odors emitted from 
blood on the addition of sulphuric acid, prove that peculiar substances 
are contained in the blood of different individuals; the blood of a man 
of a fair complexion and that of a man of dark complexion were found 
to yield different odors; the blood of animals also differed in this re- 
spect very perceptibly from that of man. — L. 



THEIR MODE OF ACTION. 369 

accompanied by an abnormal condition of growth and in- 
crease in the size of the body, and of each individual 
part of it. Hence there must be a much larger quantity 
of foreign substances, not belonging to the organism, dif- 
fused through every part of the blood in the body of a 
young individual. 

When the organs of secretion are in proper action, 
these substances will be removed from the system ; but 
when the functions of those organs are impeded, they 
will remain in the blood or become accumulated in par- 
ticular parts of the body. The skin, lungs, and other 
organs, assume the functions of the diseased secreting 
organs, and the accumulated substances are eliminated 
by them. If, when thus exhaled, they happen to be in 
the state of progressive transformation, these substances 
are contagious, that is, they are able to produce the 
same state of disease in another healthy organism, pro- 
vided the latter organism is susceptible of their action, — 
or in other words, contains a matter capable of suffering 
the same process of decomposition.* 

The production of matters of this kind, which render 
the body susceptible of contagion, may be occasioned 
by the manner of living, or by the nutriment taken by an 
individual. A superabundance of strong and otherwise 
wholesome food may produce them, as well as a de- 
ficiency of nutriment, uncleanliness, or even the use of 
decayed substances as food. 

All these conditions for contagion must be considered 
as accidental. Their formation and accumulation in the 

* Cold meat is always in a state of decomposition, that is, in a state 
of eremacausis ; it is possible that this state may be communicated to 
the system of a feeble individual, and may be one of the sources of 
consumption. — L, 



370 POISONS, CONTAGIONS, MIASMS. 

body may be prevented, and they may even be removed 
from it without disturbing its most important functions or 
health. Their presence is not necessary to life. 

The action, as well as the generation of the matter of 
contagion is, according to this view a chemical process 
participated in by all substances in the living body, and 
by all the constituents of those organs in which the vital 
principle does not overcome the chemical action. The 
contagion, accordingly, either spreads itself over every 
part of the body, or is confined particularly to certain 
organs, that is, the disease attacks all the organs or only 
a few of them, according to the feebleness or intensity 
of their resistance. 

]n the abstract chemical sense, reproduction of a con- 
tagion depends upon the presence of two substances, 
one of which becomes completely decomposed, but 
Communicates its own state of transformation to the 
second. The second substance thus thrown into a state 
of decomposition is the newly formed contagion. 

The second substance must have been originally a 
constituent of the blood ; the first may be a body acci- 
dentally present ; but it may also be a matter necessary 
to life. If both be constituents indispensable for the 
support of the vital functions of certain principal organs, 
death is the consequence of their transformation. But 
if the absence of the one substance which was a con- 
stituent of the blood do not cause an immediate cessation 
of the functions of the most important organs, if they 
continue in their action, although in an abnormal condi- 
tion, convalescence ensues. In this case, the products 
of the transformations still existing in the blood are used 
for assimilation, and at this period secretions of a pecu- 
liar nature are produced. 



THEIR MODE OF ACTION. 371 

When the constiluent removed from the blood is a 
product of an unnatural manner of living, or when its 
formation takes place only at a certain age, the suscepti- 
bility of contagion ceases upon its disappearance. 

The effects of vaccine matter indicate that an acciden- 
tal constituent of the blood is destroyed by a peculiar 
process of decomposition, which does not affect the 
other constituents of the circulating fluid. 

If the manner in which the precipitated yeast of Bava- 
rian beer acts (page 317) be called to mind, the modus 
operandi of vaccine lymph can scarcely be matter of 
doubt. 

Both the kind of yeast here referred to and the ordi- 
nary ferment are formed from gluten, just as the vaccine 
virus and the matter of smallpox are produced from the 
blood. Ordinary yeast and the virus of human small- 
pox, however, effect a violent tumultuous transformation, 
the former in vegetable juices, the latter in blood, in 
both of which fluids respectively their constituents are 
contained, and they are reproduced from these fluids with 
all their characteristic properties. The precipitated yeast 
of Bavarian beer on the other hand acts entirely upon the 
sugar of the fermenting liquid and occasions a very pro- 
tracted decomposition of it, in which the gluten which is 
also present takes no part. But the air exercises an in- 
fluence upon the latter substance, and causes it to assume 
a new form and nature, in consequence of which this 
kind of yeast also is reproduced. 

The action of the virus of cowpox is analogous to 
that of the low yeast ; it communicates its own state of 
decomposition to a matter in the blood, and from a second 
matter is itself regenerated, but by a totally different 
mode of decomposition ; the product possesses the mild 
form, and all the properties of the lymph of cowpox. 



372 POISONS, CONTAGIONS, MIASMS. 

The susceptibility of infection by the virus of human 
smallpox must cease after vaccination, for the substance 
to the presence of which this susceptibility is owing has 
been removed from the body by a peculiar process of 
decomposition artificially excited. But this substance 
may be again generated in the same individual so that he 
may again become liable to contagion, and a second or a 
third vaccination will again remove the peculiar substance 
from the system. 

Chemical actions are propagated in no organs so easily 
as in the lungs, and it is well known that diseases of the 
lungs are above all others frequent and dangerous. 

If it is assumed that chemical action and the vital prin- 
ciple mutually balance each other in the blood, it must 
further be supposed that the chemical powers vvill have a 
certain degree of preponderance in the lungs, where the 
air and blood are in immediate contact ; for these organs 
are fitted by nature to favor chemical action ; they offer 
no resistance to the changes experienced by the venous 
blood. 

The contact of air with venous blood is limited to a 
very short period of lime by the motion of the heart, 
and any change beyond a determinate point is, in a cer- 
tain degree, prevented by the rapid removal of the blood 
which has become arterialized. Any disturbance in the 
functions of the heart, and any chemical action from 
without, even though weak, occasions a change in the 
process of respiration. Solid substances also, such as 
dust from vegetable, (meal,) animal, (wool,) and inor- 
ganic bodies, act in the same way as they do in a satu- 
rated solution of a salt in the act of crystallization, that 
is, they occasion a deposition of solid matters from the 
blood, by which the action of the air upon the latter is 
altered or prevented. 



THEIR MODE OF ACTION. 373 

When gaseous and decomposing substances, or those 
which exercise a chemical action, such as sulphuretted 
hydrogen and carbonic acid, obtain access to the lungs, 
they meet with less resistance in this organ than in any 
other. The chemical process of slow combustion in 
the lungs is accelerated by all substances in a state of de- 
cay or putrefaction, by ammonia and alkalies ; but it is 
retarded by empyreumatic substances, volatile oils, and 
acids. Sulphuretted hydrogen produces immediate de- 
composition of the blood, and sulphurous acid combines 
with the substance of the tissues, the cells, and mem- 
branes. 

When the process of respiration is modified by con- 
tact with a matter in the progress of decay, when this 
matter communicates the state of decomposition, of 
which it is the subject, to the blood, disease is produced. 

If the matter undergoing decomposition is the product 
of a disease, it is called contagion ; but if it is a product 
of the decay or putrefaction of animal and vegetable sub- 
stances, or if it acts by its chemical properties, (not by 
the state in which it is,) and therefore enters into combi- 
nation with parts of the body, or causes their decompo- 
sition, it is termed mia^m. 

Gaseous contagious matter is a miasm emitted from 
blood, and capable of generating itself again in blood. 

But miasm properly so called, causes disease without 
being itself reproduced. 

All the observations hitherto made upon gaseous con- 
tagious matters prove, that they also are substances in a 
state of decomposition. When vessels filled with ice 
are placed in air impregnated with gaseous contagious 
matter, their outer surfaces become covered with water 
containing a certain quantity of this matter in solution. 
32 



374 POISONS, CONTAGIONS, MIASMS. 

This water soon becomes turbid, and in common language 
putrefies, or, to describe the change more correctly, the 
state of decomposition of the dissolved contagious matter 
is completed in the water. 

All gases emitted from putrefying animal and vegetable 
substances in processes of disease, generally possess a pe- 
culiar nauseous offensive smell, a circumstance which, in 
most cases, proves the presence of a body in a stale of 
decomposition. Smell itself may in many cases be con- 
sidered as a reaction of the nerves of smell, or as a re- 
sistance offered by the vital powers to chemical action. 

Many metals emit a peculiar odor when rubbed, but 
this is the case with none of the precious metals, — those 
which suffer no change when exposed to air and moisture. 
Arsenic, phosphorus, musk, the oils of linseed, lemons, 
turpentine, rue, and peppermint, possess an odor only 
when they are in the act of eremacausis (oxidation at 
common temperatures). 

The odor of gaseous contagious matters is owing to 
the same cause ; but it is also generally accompanied by 
ammonia, which may be considered in many cases as the 
means through which the contagious matter receives a 
gaseous form, just as it is the means of causing the smell 
of innumerable substances of little volatility, and of many 
which have no odor. (Robiquet.)* 

Ammonia is very generally produced in cases of dis- 
ease ; it is always emitted in those in which contagion is 
generated, and is an invariable product of the decom- 
position of animal matter. The presence of ammonia in 
the air of chambers in which diseased patients lie, par- 
ticularly of those afflicted with a contagious disease, may 

* Jinn, de Chivi. et de Phijs., t. xv. p. 27. 



THEIR MODE OF ACTION. 375 

be readily detected ; for the moisture condensed by ice 
in the manner just described, produces a white precipi- 
tate in a solution of corrosive sublimate, just as a solution 
of ammonia does. The ammoniacal salts also, which 
are obtained by the evaporation of rain water after an 
acid has been added, when treated with lime so as to set 
free their ammonia, emit an odor most closely resembling 
that of corpses, or the peculiar smell of dunghills. 

By evaporating acids in air containing gaseous conta- 
gions, the ammonia is neutralized, and we thus prevent 
further decomposition, and destroy the power of the con- 
tagion, that is, its state of chemical change. Muriatic 
and acetic acids, and in several cases nitric acid, are to 
be preferred for this purpose before all others. Chlorine 
also is a substance which destroys ammonia and organic 
bodies with much facility ; but it exerts such an injurious 
and prejudicial influence upon the lungs, that it may be 
classed amongst the most poisonous bodies known, and 
should never be employed in places in which men 
breathe. 

Carbonic acid and sulphuretted hydrogen, which are 
frequently evolved from the earth in cellars, mines, wells, 
sewers, and other places, are amongst the most pernicious 
miasms. The former may be removed from the air by 
alkalies ; the latter, by burning sulphur (sulphurous acid), 
or by the evaporation of nitric acid. 

The characters of many organic compounds are well 
worthy of the attention and study both of physiologists 
and pathologists, more especially in relation to the mode 
of action of medicines and poisons. 

Several of such compounds are known, which to all 
appearance are quite indifferent substances, and yet can- 
not be brought into contact with one another in water 



376 POISONS, CONTAGIONS, MIASMS. 

without suffering a complete transformation. All sub- 
stances which thus suffer a mutual decomposition, possess 
complex atoms ; ihey belong to the highest order of 
chemical compounds. For example, amygdalin, a con- 
stituent of bitter almonds, is a perfectly neutral body, of a 
slightly bitter taste, and very easily soluble in water. 
But when it is introduced into a watery solution of synap- 
tas, (a constituent of sweet almonds,) it disappears com- 
pletely without the disengagement of any gas, and the 
water is found to contain free hydrocyanic acid, hydruret 
of benzule (oil of bitter almonds), a peculiar acid, and 
sugar, all substances of which merely the elements ex- 
isted in the amygdalin. The same decomposition is ef- 
fected when bitter almonds, which contain the same white 
matter as the sweet, are rubbed into a powder and 
moistened with water. Hence it happens that bitter 
almonds pounded and digested in alcohol, yield no oil of 
bitter almonds containing hydrocyanic acid, by distilla- 
tion with water ; for the substance which occasions the 
formation of those volatile substances, is dissolved by 
alcohol without change, and is therefore extracted from 
the pounded almonds. Pounded bitter almonds contain 
no amygdalin, also, after having been moistened with 
water, for that substance is completely decomposed 
when they are thus treated. 

No volatile compounds can be detected by their smell 
in the seeds of the Sinapis alba and ^S. nigra. A fixed 
oil of a mild taste is obtained from them by pressure, 
but no trace of a volatile substance. If, however, the 
seeds are rubbed to a fine powder, and subjected to dis- 
tillation with water, a volatile oil of a very pungent taste 
and smell passes over along with the steam. But if, on 
the contrary, the seeds are treated with alcohol previ- 



THEIR MODE OF ACTION. 377 

ously to their distillation with water, the residue does 
not yield a volatile oil. The alcohol contains a crys- 
talline body called sinapin, and several other bodies. 
These do not possess the characteristic pungency of the 
oil, but it is by the contact of then:i with water, and with 
the albuminous constituents of the seeds, that the vola- 
tile oil is formed. 

Thus bodies regarded as absolutely indifferent in in- 
organic chemistry, on account of their possessing no 
prominent chemical characters, when placed in con- 
tact with one another, mutually decompose each other. 
Their constituents arrange themselves in a peculiar man- 
ner, so as to form new combinations ; a complex atom 
dividing into two or more atoms of less complex consti- 
tution, in consequence of a mere disturbance in the at- 
traction of their elements. 

The white constituents of the almonds and mustard 
which resemble coagulated albumen, must be in a pecu- 
liar state in order to exert their action upon amygdalin, 
and upon those constituents of mustard from which the 
volatile pungent oil is produced. If almonds, after be- 
ing blanched and pounded, are thrown into boiling water, 
or treated with hot alcohol, with mineral acids, or with 
salts of mercury, their power to effect a decomposition 
in amygdalin is completely destroyed. Synaptas is an 
azotized body which cannot be preserved when dissolv- 
ed in water. Its solution becomes rapidly turbid, de- 
posiies a white precipitate, and acquires the offensive 
smell of putrefying bodies. 

It is exceedingly probable that the peculiar state of 

transposition into which the elements of synaptas are 

thrown, when dissolved in water, may be the cause of 

the decomposition of amygdalin, and formation of the 

32* 



3/8 POISONS, CONTAGIONS, MIASMS. 

new products arising from it. The action of synaptas 
in this respect is very similar to that of rennet upon 
sugar. 

Malt, and the germinating seeds of corn in general, 
contain a substance called diastase, which is formed 
from the gluten contained in them, and cannot be 
brought in contact with starch and water, without effect- 
ing a change in the starch. 

When bruised malt is strewed upon warm starch 
made into a paste with water, the paste, after a few min- 
utes becomes quite liquid, and the water is found to 
contain, in place of starch, a substance in many respects 
similar to gum. But when more malt is added and the 
heat longer continued, the liquid acquires a sweet taste, 
and all the starch is found to be converted into sugar of 
grapes. 

The elements of diastase have at the same time ar- 
ranged themselves into new combinations. 

The conversion of the starch contained in food into 
sugar of grapes in diabetes indicates that amongst the 
constituents of some one organ of the body a substance 
or substances exist in a state of chemical action, to 
which the vital principle of the diseased organ opposes 
no resistance. The component parts of the organ must 
suffer changes simultaneously with the starch, so that 
the more starch is furnished to it, the more energetic 
and intense the disease must become ; while if only 
food which is incapable of suffering such transformations 
from the same cause is supplied, and the vital energy is 
strengthened by stimulant remedies and strong nourish- 
ment, the chemical action may finally be subdued, or 
in other words, the disease cured. 



THEIR MODE OF ACTION. 379 

The conversion of starch into sugar may also be ef- 
fected by pure gluten, and by dilute mineral acids. 

From all the preceding facts, we see that very va- 
rious transpositions, and changes of composition and 
properties, may be produced in complex organic mole- 
cules, by every cause which occasions a disturbance in 
the attraction of their elements. 

When moist copper is exposed to air containing car- 
bonic acid, the contact of this acid increases the affinity 
of the metal for the oxygen of the air in so great a 
degree that they combine, and the surface of the cop- 
per becomes covered with green carbonate of copper. 
Two bodies, which possess the power of combining 
together, assume, however, opposite electric conditions 
at the moment at which they come in contact. 

When copper is placed in contact with iron, a pecu- 
liar electric condition is excited, in consequence of 
which the property of the copper to unite with oxygen 
is destroyed, and the metal remains quite bright. 

When formate of ammonia is exposed to a tempera- 
ture of 388^ F. (180° C.) the intensity and direction 
of the chemical force undergo a change, and the condi- 
tions under which the elements of this compound are 
enabled to remain in the same form cease to be present. 
The elements, therefore, arrange themselves in a new 
form ; hydrocyanic acid and water being the results of 
the change. 

Mechanical motion, friction, or agitation, is sufficient 
to cause a new disposition of the constituents of fulmin- 
ating silver and mercury, that is, to effect another ar- 
rangement of their elements, in consequence of which, 
new compounds are formed. 

We know that electricity and heat possess a decided 



380 POISONS, CONTAGIONS, MIASMS. 

influence upon the exercise of chemical affinity ; and 
that the attractions of substances for one another are 
subordinate to numerous causes which change the con- 
dition of these substances, by altering the direction of 
their attractions. In the same manner, therefore, the 
exercise of chemical powers in the living organism is 
dependent upon the vital principle. 

The power of elements to unite together, and to form 
peculiar compounds, which are generated in animals and 
vegetables, is chemical affinity ; but the cause by which 
they are prevented from arranging themselves according 
to the degrees of their natural attractions, — the cause, 
therefore, by which they are made to assume their 
peculiar order and form in the body, is the vital prin- 
ciple. 

After the removal of the cause which forced their 
union, — that is, after the extinction of life, — most 
organic atoms retain their condition, form, and nature, 
only by a vis inertice ; for a great law of nature proves 
that matter does not possess the power of spontaneous 
action. A body in motion loses its motion only when 
a resistance is opposed to it ; and a body at rest cannot 
be put in motion or into any action whatever, without 
the operation of some exterior cause. 

The same numerous causes which are opposed to 
the formation of complex organic molecules, under 
ordinary circumstances, occasion their decomposition 
and transformations when the only antagonist power, 
the vital principle, no longer counteracts the influence 
of those causes. Contact with air and the most feeble 
chemical action now effect changes in the complex 
molecules ; even the presence of any body the particles 
of which are undergoing motion or transposition is often 



THEIR MODE OF ACTION. 381 

sufficient to destroy their state of rest, and to disturb 
the statical equihbrium in the attractions of their con- 
stituent elements. An immediate consequence of this 
is, that they arrange themselves according to the differ- 
ent degrees of their mutual attractions, and that new 
compounds are formed in which chemical affinity has 
the ascendancy, and opposes any further change, while 
the conditions under which these compounds were 
formed remain unaltered. 



APPENDIX. 



GROWTH OF P1.ANTS WITHOUT MOULD. 

(See page 118.) 

" Some account of a suspended plant of Ficus Australis, 
which was grown for eight months without earth in the stove 
of the Botanic Garden at Edinburgh. By Mr. William Mac- 
nab, superintendent of the Garden." (From the 3d volume of 
the Edinburgh Philosophical Journal, p. 77. Slightly abridged.) 

" Ficus Jiustralis is a native of New South Wales, and was 
introduced into the British gardens in 1789, by the Right Hon- 
orable Sir Joseph Banks. The plant is not uncommon now in 
collections in this country, where it has been usually treated 
as a greenhouse plant; and in a good greenhouse it thrives 
tolerably well, although it seems rather more impatient of cold 
than many of the plants from the same country. 

" When I came to superintend this garden in 1810, I found 
a specimen of it among the greenhouse plants, where it re- 
mained for some time afterwards ; but owing to the bad con- 
struction of the greenhouse here, and the very hardy way in 
which I was obliged to treat the plants in that department, I 
I did not find ihejicus thrive so well as I had been accustomed 
to see it do. I concluded that it required more heat, and in the 
spring of 1811 I placed it in the stove, when it soon began to 
grow as vigorously as I had ever seen it do. 

" The stem of the plant was about a foot in height before any 
branches set out ; on one of the branches, above two feet from 
the junction with the stem, a root was put out. As soon as this 
had grown about a foot long, I placed a pot under it. As 
soon as I found this pot filled with roots, I determined to try 



384 



APPENDIX. 



whether if supplied plentifully with water it would support 
the whole plant. 

"In August, 1816, I left off watering the original large pot, 
and supplied the smaller one very freely with water ; I kept it in 
this state for about eight months, till the earth in the large pot 
was so completely dry, that I was satisfied the plant could 
receive no nourishment from it. The shruh continued quite as 
healthy and vigorous as when supplied with water at the origi- 
nal root. In the spring of 1817, I took off the large pot in 
which the original roots were, and exposed the roots to the full 
rays of the sun, by gradually shaking off the dry earth from 
among them ; this had no ill effect on the plant, as it still re- 
mained perfectly healthy; it, however, had the effect of making 
roots be put out freely all over the plant, much more so than 
had hitherto been the case. 

"In the latter end of the summer of 1817, I placed a root in 
a third pot, which was put out from a branch about three feet 
from the junction with the stem, and on the opposite side of the 
plant from that which had supported it for some time past. As 
soon as I found this pot filled with fibres, I supplied it freely 
with water, and kept the other small pot dry, as I had done 
before with the original root. I found the plant still continue 
equally vigorous as before. In the spring of 1818, I took away 
the second pot, which I had for some time kept dry, and ex- 
posed the roots gradually, as I had formerly done with those in 
the original pot. 

" The third pot, which now alone supported the plant, was 
four feet from the lower end of the stem, and very near to the 
extremity of the branch, the original roots, and the second set 
of roots, both hanging loose in the air. The plant, however, 
remained in this state for nearly a year in perfect health. In 
May, 1819, 1 took a very small pot, about two inches in diam- 
eter, and filled it with earth as I had done the others, and set 
it on the surface of the earth in the third pot which now sup- 
ported the plant. Into this small pot I introduced a root which 
came from the same branch, a little below the one which was 
in the larger (third) pot. As soon as the small pot was filled 
with roots, I supplied it freely with water, and gave the larger 
pot none but what might happen to run through tiie small one. 



APPENDIX. 385 

After remaining in this state for near two months, I cut the 
branch off between the two pots ; I still supplied the small pot 
only with water, but occasionally at this time threw a little 
water over the whole plant. It continued to look as well as it 
had done before. 

"In July last, 1819, I examined the small pot (the fourth 
used), and found it completely filled with roots, very little earth 
remaining in the pot. By this time the plant appeared to me 
to be very tenacious of life, and I determined to try whether it 
would live wholly tvithout earth. I accordingly took the small 
(fourth) pot off, and gradually worked off what little earth 
remained among the roots. I at this time, however, threw 
plenty of water over the leaves, generally twice in the day: 
this was done about the latter end of July, when the weather 
was very warm, but it seemed to have no bad effects on the 
Ficus. 

" What may appear rather remarkable, is, that though this 
Ficus is a plant by no means free in producing fruit in the 
usual way of cultivating it, this specimen, quite suspended with- 
out a particle of earth, was loaded with figs during the months 
of September, October, and part of November. Two fruit were 
produced at the axilla of almost every leaf, and these were 
quite as large as I had ever seen on the plant in the hothouses 
of Kew garden. The plant is beginning to grow or extend, 
although it has now been suspended for eight months without 
a particle of earth, and during that time we have had very hot 
weather, and also very cold weather. Roots have been put out 
very freely all over the stem and branches during that time. 
The plant now (February, 1819,) measures 7^ feet between 
the extremity of the root and the top of the branches, and the 
stem at the thickest part is 5^ inches in circumference." 



33 



386 APPENDIX. 



EXPERIMENTS AND OBSERVATIONS ON THE ACTION OF CHAR- 
COAL FROM WOOD ON VEGETATION. BY EDWARD LUCAS. 

(See page 118.) 

" In a division of a low hothouse in the botanical garden at 
Munich, a bed was set apart for young tropical plants, but in- 
stead of being filled with tan, as is usually the case, it was filled 
with the powder of charcoal, (a material which could be easily 
procured,) the large pieces of charcoal having been previously 
separated by means of a sieve. The heat was conducted by 
means of a tube of white iron into a hollow space in this bed' 
and distributed a gentle warmth, sufficient to have caused tan 
to enter into a state of fermentation. The plants placed in this 
bed of cliarcoal quickly vegetated, and acquired a healthy ap- 
pearance. Now, as always is the case in such beds, the roots 
of many of the plants penetrated through the holes in the bot- 
tom of the pots, and then spread themselves out ; but these plants 
evidently surpassed in vigor and general luxuriance, plants 
grown in the common way, for example, in tan. Several of 
them, of which I shall only specify the beautiful Thunhergia 
alata, and the genus Peireskia, throve quite astonishingly ; the 
blossoms of the former were so rich, that all who saw it affirmed 
Ihey had never before seen such a specimen. It produced, also, 
a number of seeds without any artificial aid, while in most 
cases it is necessary to apply the pollen by the hand. The 
PeireskicE grew so vigorously, that the P. aculeata produced 
shoots several ells in length, and the P. grandifolia acquired 
leaves of a foot in length. These facts, as well as the quick 
germination of the seeds which had been scattered spontane- 
ously, and the abundant appearance of young Filines, naturally 
attracted my attention, and I was gradually led to a series of 
experiments, the results of which may not be uninteresting ; 
for, besides being of practical use in tlie cultivation of most 
plants, they demonstrate also several facts of importance to 
physiology. " The first experiment which naturally suggested 
itself, was to mix a certain proportion of charcoal with the earth 
in which different plants grew, and to increase its quantity 
according as the advantage of the method was perceived. An 



APPENDIX, 387 

addition of | of charcoal, for example, to vegetable mould, ap- 
peared to answer excellently for the Gesneria, and Gloxynia, 
and also for the tropical Aroidece. with tuberous roots. The two 
first soon excited the attention of connoisseurs, by the great 
beauty of all their parts and their general appearance. They 
surpassed very quickly those cultivated in the common way, 
both in the thickness of their stems and dark color of their 
leaves ; their blossoms were beautiful, and their vegetation last- 
ed much longer than usual, so much so, that in the middle of last 
November, when other plants of the same kinds were dead, these 
were quite fresh and partly in bloom. Aroidece, took root very 
rapidly, and their leaves surpassed much in size the leaves of 
those not so treated : the species, which are reared as orna- 
mental plants on account of the beautiful coloring of their 
leaves, (I mean, such as the Caladium bicolor, Pidum, Pacilt, 
&c.,) were particularly remarked for the liveliness of their tints; 
and it happened here, also, that the period of their vegetation 
was unusually long. A cactus planted in a mixture of equal 
parts of charcoal and earth throve progressively, and attained 
double its former size in the space of a few weeks. The use of 
the charcoal was very advantageous with several of the Brome- 
liacea, and Liliacece, with the Citrus and Begonia also, and even 
with the PalmoR. The same advantage was found in the case 
of almost all those plants for which sand is used, in order to 
keep the earth porous, when charcoal was mixed with the soil 
instead of sand; the vegetation was always rendered stronger 
and more vigorous. 

" At the same time that these experiments were performed 
with mixtures of charcoal with different soils, the charcoal was 
also used free from any addition, and in this case the best re- 
sults were obtained. Cuts of plants from different genera 
took root in it well and quickly ; I mention here only the Eu- 
phorbia fastuosa and falgens which took root in ten days, Pa7^~ 
danus utilis in three months, P. amaryllif alius, ChamoEdorea 
elatior in four weeks, Piper nigrum, Begonia, Ficus, Cecropia, 
Chiococca, Buddlcja, Hakea, Phyllanthus, Capparis, Laurus, 
Slifflia, Jacquinia, Mimosa, Cactus, in from eight to ten days, 
and several others amounting to forty species, including Ilex, 
and many others. Leaves, and pieces of leaves, and even pe- 



388 APPENDIX. 

(lunculi, or petioles, took root and in part budded in pure clinr- 
coal. Amongst otiicrs we mny mention the fidiola of several of 
tilt: Cijcadcn; as having taken root, as also did part of the leaves 
of the licgonia Tclsairia', and Jacaranda brasiliensis ; leaves of 
the Euphorbia Jasluosa, Oxalia Bitrrilieri, Ficus, Cyclamen, 
Polyanihes, Meseinhrianlhtmum ; also, the delicate leaves of the 
Lopho.tpcrmum and Martijnia, pieces of u leaf of the JJgnve 
.^incricanit ; tufts of Piniis, &c. ; and all without the aid of a 
previously formed bud.* 

*' Pure charcoal acts excellently as a means of curing unheal- 
thy plants. A Dorianlhes excelsa, for example, which had been 
droojjinfj for tiiree years, was rendered coniplelcly healthy in a 
very short time by this means. An orange tree which had the 
very connnon disease in which the leaves become yellow, ac- 
quired within four weeks its healthy green color, when the up- 
per surface of the earth was removed from the pot in which it 
was contained, and a ring of charcoal of an inch in thickness 
strewed in its place around the periphery of the pot. The same 
was the case wiih the Gardenia. 

" I should be led too far were I to state all the results of the 
experiments which I have made with charcoal. The object of 
this paper is merely to show the general effect exercised by this 
sub.stance on vegetation, but the reader who takes particular 
interest in tiie subject, will find more extensive observations in 
the "Jlllgemeine dculsche Gartenzeilung" of Otto and Dietrich, 
in Berlin, f 

"The charcoal employed in these experiments was the dust- 
like powder of charcoal from firs and jiines, such as is used iii 
the forges of blacksmiths, and may be easily procured in any 
quantity. It was found to have most effect when allowed to lie 

* The cuttings of several of these plants being full of moisture, re- 
quire to be partially dried before they are placed in the soil, and are 
witli diibciilly nmde to strike root in the usual method. The clmr- 
coiil is probably useful from its absorbing aiui antiseptic power. The 
Ilakea is extremely difRcuU to pro])niratc from cuUini>s. All the Lau- 
rits tribe are obstinate, sonic of them have not rooted under three 
years from the time of planting. — IV. 

I See an account of these experiments in Loudon's Gardener's 
Magazine, for March, ]b41 



APPENDIX. 389 

during the winter exposed to the action of the air. In order to 
ascertain the effects of different kinds of charcoal, experiments 
were also made upon that obtained from the hard woods and 
peat, and also upon animal chiircoal, although I foresaw the 
probal)ilit.y that none of them would answer so well as that of 
pine-wood, both on account of its porosity and the ease with 
which it is decomposed. 

"It is superfluous to remark, that in treating plants in the 
manner here described, they must be plentifully supplied with 
water, since the air having such free access penetrates and 
dries the roots, so that unless this precaution is taken, the fail- 
ure of all such experiments is unavoidable. 

"The action of charcoal consists primarily in its preserving 
tiie parts of the plants with which it is in contact; whether 
they be roots, branches, leaves, or pieces of leaves, unchanged 
in their vital power for a long space of time, so that the plant 
obtains time to develop the organs which are necessary for its 
further support and propagation. There can scarcely be a doubt 
also that the charcoal undergoes decomposition ; for after being 
used five or six years it liccomes a coaly earth ; and if this is 
the case, it must yield carbon, or carbonic oxide, abundantly 
to the plants growing in it, and thus afford the principal sub- 
stance necessary for the nutrition of vegetables. In what other 
manner indeed can we explain the deep green color and great 
luxuriance of the leaves and every part of the plants, which 
can be obtained in no other kind of soil, according to the opinion 
of men well qualified to judge ? It exercises likewise a favor- 
able influence by decomposing and absorbing the matters ab- 
sor))ed [query, excreted] by the roots, so as to keep the soil 
free from the putrefying sub.stances which are often the cause 
of the death of the spongiolfB. Its porosity as well as the power 
which it possesses, of absorbing water with rapidity, and, after 
its saturation, of allowing all other water to sink through it, 
are causes also of its favorable effects. These experiments 
show what a close affinity the component parts of charcoal have 
to all plants, for every experiment was crowned with success, 
although plants belonging to a great many different families 
were subjected to trial." — {Buchner^s Reptrlorium, ii. Reihe, 
xix. Bd. S. 38.) 

33* 



390 



APPENDIX. 



O.V THE ROTATION OF CROPS AT BINGEN ON THE RHINE. 

(See page 217.) 

The alternation of crops with esparsette and lucern is now 
•JrliVersally adopted in Bingen and its vicinity as well as in the 
Palatinate ; the fields in these districts receive manure only 
once every nine years. In the first year after the land has 
been manured, turnips are sown upon it, in the next following 
years barley, with esparsette or lucern ; in the seventh year 
potatoes, in the eighth wheat, in the ninth barley ; in the tenth 
year it is manured, and then the same rotation again takes 
place. 



ON A MODE OF MANURING VINES. 

The observations contained in the following pages should be 
extensively known, because they furnish a remarkable proof of 
the principles which have been stated in the preceding part of 
the work, both as to the manner in which manure acts, and on 
the origin of the carbon and nitrogen of plants. 

They prove that a vineyard may be retained in fertility with- 
out the application of animal matters, when the leaves and 
branches pruned from the vines are cut into small pieces and 
used as manure. According to the first of the following state- 
ments, both of which merit complete confidence, the perfect 
fruitfulness of a vineyard has been maintained in this manner 
for eight years, and according to the second statement, for ten 
years. 

Now, during this long period, no carbon was conveyed to the 
soil, for that contained in the pruned branches was the produce 
of the plant itself, so that the vines were placed exactly in the 
same condition as trees in a forest which received no manure. 
Under ordinary circumstances a manure containing potash must 
be used, otherwise the fertility of the soil will decrease. This 
is done in all wine countries, so that alkalies to a very con- 
siderable amount must be extracted from the soil. 



APPENDIX. 391 

When, however, the method of manuring now to be described 
is adopted, the quantity of alkalies exported in the wine does 
not exceed that which the progressive disintegration of the soil 
every year renders capable of being absorbed by the plants. 
On the Rhine 1 litre of wine is calculated as ■ the yearly pro- 
duce of a square metre of land (10.8 square feet English). Now 
if we suppose that the wine is three fourths saturated with 
cream of tartar, a proportion much above the truth, then we 
remove from every square metre of land with the wine only 1.8 
gramme of potash. 1000 grammes (1 litre) of champagne yield 
only 1.54, and the same quantity of Waclienheimer 1.72 of a 
residue which after being heated to redness is found to consist 
of carbonates. 

One vine-stock, on an average, grows on every square metre 
of land, and 1000 parts of the pruned branches contain 56 to 
60 parts of carbonate, or 38 to 40 parts of pure potash. Hence 
it is evident that 45 grammes, or 1 ounce, of these branches 
contain as much potash as 1000 grammes (1 litre) of wine. But 
from ten to twenty times this quantity of branches are yearly 
taken from the above extent of surface. 

In the vicinity of Johannisberg, Rudesheim, and Budesheim, 
new vines are not planted after the rooting out of the old 
stocks, until the land has lain for five or six years in barley and 
esparsette or lucern ; in the sixth year the young stocks are 
planted, but not manured till the ninth. 



ON THE MANURING OF THE SOIL IN VINEYARDS.* 

" In reference to an article in your paper. No. 7, 1838, and 
No. 29, 1839, I cannot omit the opportunity of again calling the 
public attention to the fact that nothing more is necessary for 
the manure of a vineyard, than the branches which are cut from 
the vines themselves. 

* Slightly abridged from an article by M. Krebs, of Seeheirn in the 
*' Zeiischrift fur die landwirthschafdichen Vereine des Grosherzogihvms 
Hessen." No. 28, July 9, 1840. 



392 APPENDIX. 

" My vineyard has been manured in this way for eight years, 
without receiving any other kind of manure, and yet more 
beautiful and richly laden vines could scarcely be pointed out. 
I formerly followed the method usually practised in this district, 
and was obliged in consequence to purchase manure to a large 
amount. This is now entirely saved, and my land is in excel- 
lent condition. 

" When I see the fatiguing labor used in the manuring of 
vineyards, — horses and men toiling. up the mountains with 
unnecessary materials, — I feel inclined to say to all, Come to 
my vineyard and see how a bountiful Creator has provided that 
vines shall manure themselves, like the trees in a forest, and 
even better than they ! The foliage falls from trees in a forest, 
only when they are withered, and they lie for years before they 
decay ; but the branches are pruned from the vine in the end 
of July or beginning of August whilst still fresh and moist. If 
they are then cut into small pieces and mixed with the earth, 
they undergo putrefaction so completely, that, as I have learned 
by experience, at the end of four weeks not the smallest trace 
of them can be found." 

'■'■ Remarks of the editor. — We find the following notices of 
the same fact in Henderson's ' History of Wines of the old and 
new time': — 

" ' The best manure for vines is the branches pruned from the 
vines themselves, cut into small pieces, and immediately mixed 
with the soil.' 

" These branches were used as manure long since in the 
Bergstrasse. M. Frauenfelder says ; * 

" ' I remember that twenty years ago, a man called Peter 
Miiller had a vineyard here which he manured with the branches 
pruned from the vines, and continued this practice for thirty 
years. His way of applying them was to hoe them into the 
soil after having cut them into small pieces. 

"'His vineyard was always in a thriving condition ; so much 
so indeed, that the peasants here speak of it to this day wonder- 

* Badisches landwirthschnftliches Wochenblatt, v. 1834. S. 52 und 79. 



APPENDIX. 393 

ing that old Miiller had so good a vineyard, and yet used no 
manure.' 

"Lastly, Wilhelm Ruf, of Schriesheim, writes ; 

" ' For the last ten years I have been unable to place dung 
on my vineyard, because I am poor and can buy none. But 
I was very unwilling to allow my vines to decay, as they are 
my only source of support in my old age ; and I often walked 
very anxiously amongst them, without knowing what I should 
do. At last my necessities became greater, which made me- 
more attentive, so that I remarked that the grass was longer on 
some spots where the branches of the vine fell than on those on 
which there were none. So I thought upon the matter, and 
then said to myself: If these branches can make the grass 
large, strong, and green, they must also be able to make my 
plants grow better, and become strong and green. I dug there- 
fore my vineyard as deep as if I would put dung into it, and 
cut the branches into pieces, placing them in the holes and 
covering them with earth. In a year I had the very great 
satisfaction to see my barren vineyard become quite beautiful. 
This plan I continued every year, and now my vines grow 
splendidly, and remain the whole summer green, even in the 
greatest heat. 

" ' All my neighbours wonder very much how my vineyard is 
so rich, and that I obtain so many grapes from it, and yet they 
all know that I have put no dung upon it for ten years.' " 

Illustration of Fermentation. 

(See page 275.) 

When yeast is made into a thin paste with water, and I cubic 
centimetre of this mixture introduced into a graduated glass 
receiver filled with mercury, in which are already 10 grammes 
of a solution of cane-sugar, containing 1 gramme of pure solid 
sugar ; it is found, after the mixture has been exposed for 24 
hours to a temperature of from 20 to 25° C. (68 — 77°F.), that a 
volume of carbonic acid has been formed, which, at 0° C. (32*' F.) 
and an atmospheric pressure indicated by 0.76 metre Bar. would 
be from 245 to 250 cubic centimetres. But to this quantity we 
must add 11 cubic centimetres of carbonic acid, with which the 



394 APPENDIX. 

11 grammes of liquid would be saturated, so that in all 255 — 
259 cubic centimetres of carbonic acid are obtained. This 
volume of carbonic acid corresponds to from 0.503 to 0.5127 
gramme by weight. 



DR. DANA'S VIEWS RESPECTING GEINE. 

In the Report on a Reexamination of the Economical Geology 
of Massachusetts, by Professor E. Hitchcock, 1838, Dr. S. L. 
Dana lias described a method of analyzing soils, and presented 
us with his views of the state in which vegetable and animal 
matter exists in them, and the changes which it undergoes 
before being taken up by plants. 

Dr. Dana is of opinion that air and moisture convert insoluble 
into soluble geine, and that there is no problem of greater 
practical importance to be solved in agricultural chemistry than 
the determination of the quantity of these substances in soils. 
It lies, he remarks, at the foundation of all successful cultiva- 
tion, and its importance has been undervalued. Earths and 
geine are what is essential to fertility, and soils will be fertile 
in proportion as geine is mixed witli the earths. 

"Among the many economical modes of producing geine, the 
ploughing in of vegetable matter has held a high rank. Nature 
teaches us to turn in the dry plant. Dried leaves are her 
favorite morsels, and the very fact, that Nature always takes 
the dried plant, from which to prepare the food for growing 
vegetables, should have taught us long ago, the wisdom of 
ploughing in dry crops." The careful collecting and husband- 
ing of dry leaves needs not to be urged upon the intelligent 
agriculturist. 

The proportion of geine in different soils as stated by Dr. 
Dana have been given at page 59. 

Application of Solution of Geine. 

In the Appendix to the Third Report of the Agriculture of 
Massachusetts, 1840, by Dr. Colman, is a statement of Mr. Nich- 
ols, of Danvers, of the results of the practical application of Dr. 
Dana's views, from which the following extracts are made. Dr. 



APPENDIX. 395 

Dana's directions for preparing a solution of geine are as fol- 
lows : Boil one hundred pounds of dry, pulverized peat with two 
and a half pounds of white ash, (an article imported from Eng- 
land,) containing 36 to 55 per cent, of pure soda, or its equiva- 
lent in pearlash or potash, in a potash kettle, with 130 gallons 
of water ; boil for a few hours, let it settle, and dip off the clear 
liquor for use. Add the same quantity of alkali and water, boil 
and dip off as before. The dark colored brown solution con- 
tains about half an ounce per gallon of vegetable matter. It 
is to be applied by watering grain crops, grass lands, or in any 
other way the farmer's quick wit will point out. In the month 
of June, I prepared a solution of geine, (says Mr. N.) obtained 
not by boiling, but by steeping the mud as taken from the mead- 
ow, in a weak lye in tubs. The proportion was about, — peat 
100 lbs., potash 1 lb., water 50 gallons ; stirred occasionally for 
about a week, when the dark brown solution, described by Dr. 
Dana, was dipped off and applied to some rows of corn, a por- 
tion of a piece of starved barley, and a bed of onions sown on 
land not well prepared for that crop. The crop of barley on 
the portion watered was more than double the quantity both 
in straw and grain to that on other portions of the field, the 
soil and treatment of which were otherwise precisely similar. 

In June, four rows (of the onions) were first watered with 
the solution of geine. In ten days, the onions in these rows 
were nearly double the size of the others. All but six rows of 
the remainder were then watered. The growth of these soon 
outstripped the unwatered remainder. Eventually the whole 
piece was watered with the solution, excepting the ends of some 
of tlie rows, which produced only very small onions, and, had it 
not been done, Mr. Nichols believes that not a single bushel of 
a good size would have been produced. The onions when 
measured, making ample allowance for the tops which had not 
been stripped off, were adjudged equal to four bushels to the 
square rod, or at the rate of 640 bushels to the acre. 

On the JVaiure of Geine. 

In consequence of the difference of opinion in regard to the 
substance which has been called geine, and which has been 
made public in the Agricultural Reports and Scientific Journals, 



396 APPENDIX. 

it was deemed desirable, and due to the advocates of opposite 
views, to proffer to them the opportunity of appending to this 
volume such remarks as they might be desirous of presenting 
in addition to, or in support of, what they have already given to 
the public. From the replies to the letters addressed to the gen- 
tlemen who have advocated the different views, the following 
extracts are given, together with an extract from the forthcoming 
Final Report on the Economical Geologi) of this State, for which 
I am indebted to the politeness of its distinguished author. Pro- 
fessor Hitchcock, of Amherst. It will be obvious that Liebig is 
conceived to have taken but a limited view of the action of 
geine. — W. 

Extract from a letter to Professor Hitchcock, from S. L. Dana, 
M. D., of Loivell, dated March 18th, 1841. 

"It appears to me, that some of our friends seem to forget the 
foundation on which we have laid, I may not say an edifice, but 
the staging and scantling for them to build by. We have spoken 
of geine 1st. Agriculturally; 2d. Chemically. 

" Agriculturally, we define it to be ' all the decomposed organic 
matter of the soil.' It is soluble or insoluble, including in this 
its salts. These salts are soluble in, or decomposed by alkalies. 
In these states it is the food of plants. Now this is an agricul- 
tural and practical view. It was to these points to which all my 
letters in your 2d Report tended. I avoided all discussion about 
the how of its operation, and its chemical constitution. Mr. Col- 
man addressed such queries to me, that I touched on these 
points. I stated to him my belief that these were 'forms of 
geine.' I have stated to you, that I believed crenic and apocrenic 
acid bear such a relation to geine. When, still later. Dr. Jack- 
son denied the existence of geine, and asserted it to be a com- 
pound only of these acids, I admitted his discovery, and have at 
tempted to show how this is compatible with the existence of 
geine as a distinct principle. What, then, is geine.' — and now 
we speak chemically. Did we and Berzelius mean the same 
thing when speaking in this sense ? and does Berzelius now 
deny, that what he called geine in 1833, no longer exists ? He 
may have dropped the name geine, as applicable to the three sub- 



APPENDIX. 397 

stances into which he then separated mould, — ' extract of mould,' 
'geine,' and 'carbonaceous mould,' — but he still retains 'humic 
acid.' What, then, was humic acid in his estimation, in 1833? 
He considered ulmin and humin synonymous then, and both as 
meaning geine. In his account of the attempts to fix the atomic 
weight of geine, he quotes Boullay's analysis of ulmin. So I 
understand geine, when called upon to speak of it chemically. 
So far Berzelius goes. Geine, ulmin, humin. are identical. But 
Dr. Jackson says, Berzelius has abandoned geine : its name, but 
not as a principle. 

"He still retains 'humic acid' as one of the ingredients of 
soil. We have shown, that this was his geine, 1833. He still. 
then, admits geine as a separate, independent principle. It is 
the same which we call geine, when speaking chemically. Ber- 
zelius has dropped the name only as applicable to his tbree/ornis 
of geine ; we retain it, for all forms, speaking agriculturally. I 
have shown in my letter to you, relating to Dr. Jackson's discov- 
eries of the compound nature of geine, that Berzelius, in his 
Traiti de Chemie, 1833, said that crenic and apocrenic acid ex- 
isted in soils. If Dr. Jackson was ignorant of this, he probably 
was not unacquainted with Shepard's remarks on your 2d report, 
where Hermann's analysis of humus is cited, as composed of cre- 
nic, apocrenic, and ulmic acids. I trust Dr. Jackson does not 
claim to be the discoverer of the first named acids in soil. If he 
is not, what new views has Berzelius appeared to support as pe- 
culiarly Dr. Jackson's. Berzelius may have new views, but I do 
not yet understand them enough to see wherein they conflict 
with his former statements, or controvert the position we have 
taken. To be sure, I only know them from the printed reports 
of Dr. Jackson's remarks at the late Agricultural Meeting in 
Boston. As regards Liebig, there are so many points to be set- 
tled in vegetable physiology, that his views can be considered, 
at present, only as highly ingenious, bold, and counter to expe- 
rience. 

" But still, as you request my views on one point of his argu- 
ment, I give them as they occur, and am glad so to do, as it 
allows me to say, that there is a point on which we are over- 
looked ; I mean the action of growing plants upon silicates.* 

" * See my letter to Mr. Colinan, in his 2d report." 

34 



398 APPENDIX. 

" Growing plants decompose silicates. Potash and other bases 
are let loose upon geine. That becomes soluble. Now, whether 
this is or is not taken up by plants, or only thus extended and 
divided, so that the air easier acts on it, to evolve carbonic acid, 
you will perceive, that so long as the plant is vigorous and grow- 
ing, so much the more is geine rendered soluble. The plant ceas- 
ing its functions, geine loses one great source of its solubility. 
Now we have never contended, that simple geine or geates (here- 
in Liebig admits the existence of such a principle, under the name 
of humus,) are dissolved by rain only, or depend on that only 
for being put in a soluble state. If that was the case, why then 
Liebig's data being correct, his conclusion would follow. But 
this is only a partial view of the action of oxygen of air upon 
geine. It produces not only carbonic acid, but water also, by 
uniting witli the hydrogen of the geine. The amount of water 
proceeding from this cause is truly astonishing. It has been 
found by actual experiment, (see JVicholso7i^s Journal, 1809 or 
1608, I forget which,) equal, per hour, from an acre of fresh 
ploughed sward, to 950 pounds ; while the undisturbed ground 
gave not a drop. This is equal to the evaporation per hour from 
an acre after most copious rains. And to show that this depends 
upon the decomposition of the geine, the quantity of water evapo- 
rated per hour, in a dry time, from a well-manured acre, was 
found equal to 5000 pounds. (I quote from memory.) We have 
here, then, an abundant source of water to solve, in the action 
of air upon geine. If I remember Liebig, (I have seen the 
book only a few hours,) he himself says that water is a pro- 
duct of the decomposition of geine. I wonder this source of 
fluid to dissolve his geine, escaped him. Indeed it would not, if 
he had not pressed the infinitesimal small quantity which rain 
could dissolve, into his argument against the necessity of geine. 

" Liebig takes it for granted, that it is the rain only which is 
to dissolve geine and geates. He says it is not enough. We 
offer him an abundant source in the fountain of water from ge- 
ine. He may say, it is not enough. We add, if indeed we should 
not begin there, the action of growing plants upon silicates, 
evolving bases whose action upon geine renders it easily soluble. 
I think these causes of the solubility of geine enough, if no rain 
fell, and no smnll argument to prove that geine exercises other 



APPEiVDIX. 399 

functions in soil, besides evolving carbonic acid. Geine ceasing, 
barrenness follows. When Raspail and Liebig prove the con- 
trary, I '11 believe ourselves wrong in our views. 
"With great regard, 

" Ever your friend, 

"SAMUEL L. DANA." 

From Dr. Dana's Letter of June 22d, 1840, to Prof. Hitchcock.* 

" From the days of Vauquelin, who first noticed ulmin, to the 
present time, this substance has been investigated by the most 
distinguished chemists, under the name of ulmin, or humus, or 
geine. These are convertible terms, they mean one and the 
same thing. 

"Malagutti has obtained ulmic acid in distinct crystals. By 
boiling these in weak acids, a black substance is deposited, which 
he calls ulmin, identical in its composition with the acid. Once 
and for all, I consider ulmin, humus, geine, ulmic, humic, and 
geic acid, one identical substance ; whether neutral or acid its 
constitution, ever one and the same, subject to the great law of 
organic chemistry, that proximate compounds act as simple ele- 
ments," 

[For the analysis of geate of copper and geic acid, the chem- 
ical reader is referred to the Report, p. 121. From these the 
number 42 is adopted as the atomic number of geine.] 

"A substance found by different observers so identical in com- 
position, by actual analysis, whose theoretical confirms its ana- 
lytical constitution, which forms definite compounds, and whose 
history and properties are better understood than a large propor- 
tion of the objects in organic chemistry, may well be considered 
a definite chemical compound. That it is so, is believed by all 
chemists, except Raspail, whose principles would equally reduce 
the larger portion of organic substances, to carbon and water; 
and Dr. C. T. Jackson, who reduces geine into a mixture of cre- 

* This letter appears to have been written in consequence of a 
statement by Dr. Jackson, that " the substance originally mistaken by 
Berzelius, and subsequently by Dr. Dana," was only a mixture of 
crenic and apocrenic acids. — W. 



400 APPENDIX. 

nic and apocrenic acids. Others have admitted these acids in 
combination with geine, in soils. Berzelius, their discoverer, 
and to whom we are indebted for all that is known of their his- 
tory, years ago said, that crenic and apocrenic acids existed in 
soils in small quantity ; and moreover states, that these acids are 
among the general products of putrefaction. 

" The doctrine, then, that they are found in soils, is not the 
doctrine of yesterday nor of to-day, — it is no new thing; but 
the doctrine that geine is a mixture of these acids, that geine 
has no independent existence, is new ; and coming from a source 
commanding our respect, requires a careful consideration. The 
various opinions which have been formed on the subject of geine, 
owe their existence in part to the varied means which produce 
this substance. It comes from organic matter by putrefaction, 
by the action of acids and of alkalies, caustic or carbonated, by 
the action of alkaline earths, by alumina, by metallic oxides, 
acting on organic matter, especially when assisted by heat, and 
as a general law, we may say that all substances, oxidating, and 
gently acting on organic matter, produce geine. It is produced 
by fire, by heating or roasting organic matter, and hence its 
?Lbundance in soot, in crude pyroligneous acid, in charcoal, and 
baked wood. It is found in carburet of iron ; and cast iron, 
treated with acids, leaves an insoluble residue, having the prop- 
erties of geine. Of all the agents which thus change organic 
matter into geine, the action of the alkalies and of the alkaline 
earths is most powerful : next to them ranks alumina, which is 
little if at all inferior to lime, when assisted by growing plants. 
It is the decomposition of the aluminous silicate, by living plants, 
which lets loose the alumina, to convert insoluble into soluble 
geine. But to return, the mode of acting here is in many cases 
purely ^ catalytic,'' the action of presence, — the same elements 
re-arranged, a new order takes place, — while in other cases, a 
part of the original compound is removed, new substances are 
produced. In whatever way we may produce the proximate 
principle geine, whose definite constitution we see has been so 
well determined, it is not at all probable, that it proceeds, per 
saUum, from organization to its atomic constitution. There 
exist, doubtless, intermediate states, other compounds, which 
chemistry has already, or will hereafter detect ; forms of geine, 



APPENDIX. 401 

SO to speak. In this class, I include crenic and apocrenic acid. 
Nor can we determine whether these arise from a catalytic 
change in geine, or whether they are formed first, and then unite 
to produce that definite compound. But the properties and 
actions are so very distinct from those of geine, that the last 
cannot be owing to a mere mixture of the two first. From the 
small quantity in which they accompany geine in soils, it is 
probable that they derive their origin from a change in the ele- 
ments of that substance ; and if ever geine has been loholly re- 
duced to crenic and apocrenic acid, I think it is no difficult mat- 
ter to show how this result has been produced by the agent 
employed, and by the manipulation. Cases analogous are familar 
to all chemists, and the very ease witli which crenic passes into 
apocrenic acid, may help our conceptions of the possibility of a 
mere new arrangement of the elements of geine, — an arrange- 
ment producing two well defined acids, being considered as the 
separation of those which previously were only mechanically 
mixed. As evidence of the evanescent nature of crenic acid, it 
is well established, that its solution in water, by simple exposure 
to air, becomes apocrenic acid : hence its name : its existence, 
as Berzelius says, depends on crenic acid, just as apo-\heme de- 
pends for its existence on a solution of organic extract in water- 
Without crenic there can be no apocrenic acid. These acids 
have been separated. Their insulation is one of the most diffi- 
cult of chemical operations, requiring not one, but several solu- 
tions and separations by sulphuretted hydrogen before we can 
estimate their quantity, or be assured of their purity. Separated, 
their characters are as follows : — Both resemble vegetable ex- 
tract : 

Crenic acid. ..Apocrenic acid. 

Color yellow, Brown. 

Transparent, 

Amorphous, Amorphous, 

Taste acid, then astringent, Astringent. 

Excessively so\\xh\e in water and Slightly soluble in water. 

" « in alcohol. Slowly soluble in pure alcohol. 

Solution in water, precipitates 
by sal-ammoniac in flocks. 



34 



* 



402 APPENDIX. 

Crenates, Jlpocrenates. 

Of alkalios, like yellow extracts, Of alkalies, black friable mass- 
and very soluble in water, and es ; in water a dark soluble 
weak alcohol. brown color. 

Of lime, neutral, soluble in 

water, subsalt, insoluble. 
Of magnesia, easily soluble in Of alkaline earths, solve in 
water. water, yellow color. The 

subsalts quite insoluble. 
Of alumina, neutral insoluble in Of alumina, neutral, insoluble : 

water: supersalt, soluble. supersalt, soluble in water. 

Of iron, soluble in water. Of iron, protoxide, soluble in 

water: peroxide, insoluble in 
water. 

" From the statement I have already made of the elements 
which enter into soluble geine,.it will be seen that a small part 
only of soils exist, as a geic salt. The phosphoric acid I have 
enumerated among those elements, confining the term ' soluble 
geine ' in that case to all which an alkali dissolved. The phos- 
phoric acid proceeds from a partial decomposition of phosphate 
of lime, or subphosphate of alumina. It is not an element of 
geine. The iron and alumina are dissolved as salts of geine. 
We conclude that the greater part of the geine of soils exists 
uncombined. If this substance, as it exists in soils, is only a 
mixture of crenic and apocrenic acids, then, from the established 
properties of these acids and their salts, this result must follow. 
The soluble organic mutler of soils ought to be completely solved 
by tvater and alcohol. No other agents are required to detect 
not only the existence, but the total amount of these acids, to 
determine in fact the amount of soluble geine. Simply boiling 
the soil in v/ater should extract all the crenic acid. ' It is ex- 
cessively soluble in water,' says Berzelius, — so soluble, that the 
water of the Porla well, tiie source whence the acid was first 
obtained, is colored brown by it. Pure alcohol, will then dis- 
solve all the apocrenic acid ; and we may thus at once ascertain 
the amount of these acids. Admitting the properties of crenic 
and apocrenic acid, I do not see how we can escape this conclu- 
sion. Nor will it alter the case, if it be said that the acids are 



APPENDIX. 403 

combined with the bases of earths and oxides. We still are 
driven to the same conclusion. Noav this is a resultj which I 
presume the propounder of this doctrine of the mixed nature of 
geine, will not admit. He knows how very trifling is the pro- 
portion of organic matter, or its salts which yield to alcohol, or 
to water. I do not mean to deny that this little is crenic or apo- 
crenic acids or their salts. Nor will the advocates of the doc- 
trine deny, that all the crenic acid will, by exposure to air, pass 
into apocrenic acid. If, then, geine be a mixture of acids, and 
is insoluble in the agents which act easily on these acids while 
separate, we may reasonably conclude, that the elements of these 
acids have arranged themselves anew, entered into a true, chemical 
combination, to form geine, a definite proximate principle, whose 
separate, independent existence, whose properties, combinations, 
and uses, are as well established as any facts in chemistry. 

" Finding, then, that the action of water and alcohol on the 
geine of soils is Avholly different from that which ought to ensue, 
if it is a mixture of crenic and apocrenic acids, other agents 
have been employed to effe'Ct their separation. Now these 
agents are precisely those which we have enumerated above, as 
having the power to alter the arrangement of the elements of 
organic matter, or of geine ; developing either acid properties, 
without altering its constitution, or rearranging its elements, 
without addition or subtraction. The long and repeated digestion 
in carbonate of ammonia, has produced, not educed, crenic and 
apocrenic acids. — We are not informed of any other result, of 
any other product: no evolution of gas, indicating that any de- 
composition has occurred. From the acknowledged chemical 
tact of Dr. C. T. Jackson, we infer, that geine has afforded him 
only crenic and apocrenic acids. That these are the products 
of his process can then be easily understood. 

"The atomic weight of geine we have shown is 42. This 
number differs but little from the sum of the weight of two 
atoms of crenic acid, and one atom of apocrenic acid. Berzelius 
determined the atomic weight of crenic acid to be, 13.50 

of apocrenic acid, 16.50 
then 2 atoms crenic = 13.50 X 2 = 27. 

1 atom apocrenic 16.50 

43.50 



404 APPENDIX. 

Which differs only 0.89 from Boullay's number for geine, deduced 
from his analysis of ulmate of copper. But allowing the crenic 
acid to be 12.75, we have then 2 atoms = 25.50 
1 atom apocrenic = 16.50 

42.00 
And that 12.75 is probably the true number, will appear from re- 
arranging the atoms of geine, so as to constitute two atoms of 
crenic and one of apocrenic acid. — I have met with no analysis 
of the atomic constitution of these acids,* but taking their atom- 
ic weights as above, and the result of Dr. C. T. Jackson, that 
geine is wholly separated into these acids, then the number of 
the atoms constituting their weight is as follows: — 
Crenic acid. Apocrenic acid. 

Carbon, 11. = 8.25 10 == 7.50 

Hydrogen, 4.= .50 8 = 1. 

Oxygen, 4. = 4. 8 = 8. 

12.75X2+ 16.50 = 42 

The number of atoms in 42 geine is 64. as above : 

and we have one atom geine = C.^^ H." O.^^ 

Which resolved into 

2 atoms crenic acid, = C.'" H.^ O.* 
1 atom apocrenic acid, = C}° H.® O.* 



From one atom of geine, = C' H.'^ O.^* 

* " Hermann has given the following as the constitution of the cre- 
nic, apocrenic, and uhnic acids. .American Journal of Science, ^c, 
Vol. 36, p. 3G9. 

Crenic. J}pocrenic. 

Carbon, 535.0 (=7 atoms.) 1070.1 (= 14 atoms.) 

Hydrogen, 99.8 (=16 " ) 87.2 (=14 " ) 

Nitrogen, 88.5 (=1 " ) 265.5 (= 3 " ) 

Oxygen, 600.0 (=6 " ) 300.0 (= 3 " ) 

1323.3 (combining weight) 1722.9 (combining weight) 10000 
" It is hardly necessary to observe, tiiat tiiese results confirm the 
suffcestion of Dr. Dana in the text, that crenic and apocrenic acids 
were not probably so constituted, as to be entirely conveited into ge- 
ine without an excess of any of the ingredients. — E. H." 



APPENDIX. 405 

" It may be said, that it may be proved that my statement of the 
atomic constitution of these acids is not confirmed by analysis. 
So much the better. That will prove that geine cannot be a 
mixture of them. Though these elements theoretically admit of 
this arrangement, it is not at all probable, that nature forms cre- 
nie and apocrenic acids, out of which to form geine, by their 
complete chemical union ; still less is it probable, that she mere- 
ly mixes these acids. The constitution of geine is too firmly 
settled, to allow us to believe, tiiat it is a haphazard mixture. 
The evidence of the existence of a simple proximate principle, 
geine, is rather strengthened than weakened by the above view 
of its probable theoretical changes. And as Dr. Jackson states 
that he has actually separated geine into two acids, he has fur- 
nished new and unquestioned proof of the existence of that prin- 
ciple. If the sum of the weights of his crenic and apocrenic 
acids equals the weight of the organic part of his soluble geine, 
he furnishes the highest evidence we can have, of the separate, 
independent existence of that element. I believe he has seen all 
that he states, and I must ask him to believe that the conclusions 
to which we have arrived respecting the nature, constitution, and 
properties of geine are equally founded on experiment. While 
I thus freely admit the result he states, I express my conviction, 
that what he has seen he has produced, that he has merely re- 
arranged the elements of a well-known, definite compound, by 
the long-continued action of ammonia. Such changes may not 
be readily comprehended by the majority, into whose hands your 
report may fall, — all, however, now-a-days understand that there 
is such a thing as carbon, such elements as oxygen and hydro- 
gen, which last by their union produce water. Now it is evident 
by a glance at the above arrangement of the elements of geine 
and crenic and apocrenic acids, that these are each and all re- 
-solvable into carbon and water. We may as well deny the ex- 
istence of crenic and apocrenic acids because resolvable into 
carbon and water, as to deny the existence of geine because re- 
solvable into crenic and apocrenic acids. A glance, too, at the 
above arrangement, will show us how crenic becomes apocrenic 
acid by simple exposure ; for by absorbing oxygen, each atom 
parts with 6 atoms carbon, and then 2 atoms crenic form one 
of apocrenic acid ; for, — 



406 APPENDIX. 



2 atoms crenic acid 



id, I 



Carbon. Hydrogen. Oxygen. 
11 4 4 

11 4 4 



22 8 8 

Deducting 12 Carbon, 12 

Form 1 atom apocrenic, 10 8 8 

" It is this change, which may account for the great evolution of 
carbonic acid, which attends the exposure of geine to air. The 
alkaline, earthy, and metallic bases of the silicates of soils, as 
they are eliminated by the decomposing action of growing plants, 
all effect catalytic changes in geine. But without these, geine 
itself is decomposed by air and moisture, evolving volumes of 
carbonic acid. It becomes in every and the widest sense the 
food of plants, whether we consider it taken up as a simple solu- 
tion of geine, or geates, or as a prolific source of carbonic acid. 
I do not, however, consider carbonic acid as vegetable food, or as 
playing a very important part in the nutrition of plants. Jablon- 
ski tried to verify the idea of Raspail, and to determine how much 
is due to the action of carbonic acid. The whole series of hia 
most carefully conducted experiments, feeding plants only on 
carbonic acid and water, lead to this conclusion, that carbonic 
acid and water do not sustain plants, after the vegetable nutriment 
deposited in albumen or the cotyledons has been exhausted. I did 
never suppose, till I learned it from you, that any one could have 
believed that I denied that plants absorb nourishment from air. 
Speaking wholly of soils, and that by letter, I confined my re- 
marks strictly to the nourishment derived from the eartli. But 
extending the remark to air, geine is the great source of carbonic 
acid even then, and as far as carbonic acid is absorbed by the 
roots of plants, is perhaps its only source. I go further. I be- 
lieve that geine was, before organic matter, an original forma- 
tion, dating its birth from the dawning of time, when oxygen, and 
hydrogen, and carbon, were created. I believe it to have been 
an original formation, the source whence were nourished the gi- 
gantic plants of coal formations, and of itself, forming a large 
part of such deposits. Hence we find little or no alkalies in our 
analysis of coal, — a little silica, iron, lime, and alumina only 
having been formed as geates, in this early age. 



APPENDIX. 407 

" I have not thought it wortli while to go into an examination of 
the practical value, to agriculture, of the doctrine of the mixed 
nature of geine. If it has any value, it depends entirely on 
showing that crenic and apocrenic acids require different treat- 
ment from geine, and on determining the proportion in which 
these acids exist in soils. The first has not been done, the last 
never will be effected. It cannot be. We see these acids pass- 
ing from one to the other state even during our manipulations ; 
how then can we determine in what proportions they existed in 
the original soil? It may be said, that we can estimate them all, 
as crenic acid, as Berzelius has in his analysis of the water of the 
Porla well. In this case, so far as agriculture is concerned, we 
may call them geine. 

" With the highest regard, I am 

" Your friend and servant, 

« SAMUEL L. DANA. 
"Prof. Hitchcock, .^?n/ie?*5/. 

" P. S. I do not ordinarily use the oxygen scale. The state- 
ment above being chiefly derived from Dr. Thomson, 1 have 
employed his numbers for your convenient reference." 

Dr. Jackson's Vietvs. — Geine and Humus. 

Di\ Jackson is of opinion, that if there is any such matter as 
has been called soluble geine, (see note, p. 57,) lime, by forming 
an insoluble combination with it, would be one of the most nox- 
ious ingredients in soil or in composts, which is directly opposite 
to the fact as proved by experience. Dr. Jackson remarks, that 
by actual experiment he has ascertained that but a very small 
proportion of the soluble organic matter (called geine) is precipi- 
table by lime-water, and that matter is only apocrenic acid. All 
the other matters which form the largest proportion of the solu- 
ble mould, form soluble combinations with lime.* 

* According to Berzelius, subcrenate of lime is insoluble. See 
Thomson's Organic Chemistry, p. 51. On referring to the table of 
Hitchcock, p. 59, it will be seen that his result agrees with that of 
Berzelius. It is obvious that care is required to avoid an excess of 
lime and the formation of a soluble crenate. In agriculture this would 
seem to be unavoidable, and lime to be as likely to do harm as 
good. — TV. 



408 APPENDIX. 

In regard to sub-soils, although not at first sight very prepos- 
sessing in appearance, they contain, continues Dr. Jackson, a 
large amount of the most valuable soluble matters capable of 
nourishing plants, and the crenate of lime is much more abun- 
dant in them, in proportion to the other organic matters, than in 
the top-soil or mould. This he believes to have been carried 
down by infiltration ; and on this depends the theory of sub-soil 
ploughing. 

Our well waters, according to Dr. Jackson, are often charged 
with the soluble organic matters of the soil, the crenate of lime. 
So also hard water with crenates of lime, ammonia, humates of 
the same, &c. The river and pond waters of Massachusetts also 
contain crenic acid. 

Berzelius employs humus as a generic term for the organic 
matters in soils. The reason why the organic matters in nature, 
called humus, act so differently from artificial humic acid is, that 
the former is not a simple organic acid, but is a complication of 
salts, formed from decomposed organic matters, by which acids 
are combined with alkaline, and earthy, and metallic bases. 
Hence, when neutralized by bases, it has no acid reaction, but 
the moment it is set free it has. 

The substances which are confounded under the name of sol- 
uble humus, soluble geine, &c., consist of 

Crenic acid. Sulpliates of Soda, 

Apocrenic acid. Potash, 

Humic acid. Magnesia, 

Extract of Humus. Lime, 

Humin. Ammonia, &c. 

Glalrin. Phosphates of Soda, 

Soluble salts, as Ammonia, and other 

Chlorides of Sodium, bases. 

Calcium, Oxalates of various bases, not all 

RIagnesium, ascertained, 
and other clilorides and muriates. 

We have also the acids of vegetable mould, above mentioned, 
combined with all the usual bases found in soils, such as lime, 
magnesia, manganese, oxide of iron, alumina, potash, soda, &c. 
Liebig disrecrards these del ails, and calls all humus. 



APPENDIX. 



409 



Extracts from the Work of Berzelius. (C. T. J.) 

Analyses of soils from Russia, Siberia, and Hungary. Soil 
from one to two feet in depth. 

A. Soil never cultivated. B. Long cultivated, and said to be 
in an exhausted condition. C. Sub-soil of the field B. 





^. 


B. 


a 


Sand, .... 


51.84 


53 38 


52.77 


f Silica, 


17.80 


17.76 


18.65 


Alumina, 


8.90 


8.40 


8,85 


Aluminous J Per Oxide of Iron, 
matter. ' Carbonate of Lime,* 


5.47 


5.66 


5.33 


.87 


.93 


1.13 


Magnesia, . 


0.00 


.77 


.07 


[^ Water, .... 


4.08 


3 75 


4.04 


... V- J f Phosphoric Acid, 

Acids combined <-•-,.„;„ \„:a 
■iu D /^\ -J r Crenic Acid, . 
with Per Oxide of^ ^pocrenic Acid. . . 
IronandAlumina. I^jj^^^i^^^ij^ • 


.46 
2.12 
1.77 
1.77 


.46 

1.67 
2.34 

0.78 


.46 

2.56 

1,87 
1.87 


Extract of Humus, 


3.10 


220 


0.00 


Humin and rootlets, 


1.66 


1.66 


1.66 


99.84 


99.76 


99.86 



Analysis by Hermann, and given in the last fasciculus of Ber- 
zelius's Treatise on Chemistry, published in Germany, 1840. 
Humic acid is composed of 

Sprengel. Malaguti. 

Carbon, . , . 58.00 . . . 57.48 = 30 atoms. 

Hydrogen, . . 2.10 . . 4.76 = 30 " 

Oxygen, . . . 39.90 . . . 37.76 =.= 15 " 



CI. p 
w p -. 
o " 5 

p •-'i 



Difference owing to the difficulty of procuring the humic acid pure 
from the soil. 



* I am of opinion, that the carbonate of lime here reported was orig- 
inally in the soil combined with the crenic acid in wliole or in part. 

C. T. J. 

Berzelius says, "animal manures become changed after a while into 
crenic and apocrenic, humin and humic acids, in order to supply what 
has been removed by the crops that have been taken from the soil." 

35 



410 APPENDIX. 

Animal Manure. 

Animal manures become changed after a while into crenic 
and apocrenic acids, humin, and humic acid, in order to supply 
what has been removed by the crops that have been taken from 
the soil. 

Physiologists have often remarked that plants grow very well 
without the presence of humus until the formation of the organs 
of fructification, but after this has commenced and the seed 
begins to perfect itself, they draw from the earth a large supply 
of the constituents of the soil, and wanting these the blossoms 
fall off without forming any seed or fruit. 

The remarks of De Saussure on soils seem to show that the 
three constituents above described, crenic, apocrenic, aud hu- 
mic acids, by means of the reciprocal influence of water and 
air become mutually changed. Water in moist soil changes 
part of the insoluble humin into humic acid, so that after a suffi- 
cient length of time the greater part of the humin becomes 
soluble. The atmosphere on the other hand, re-forms from the 
soluble matter, humin. Coal of humus, which in contact with 
the air changes a portion of it into carbonic acid, is itself con- 
verted into humin and humic acid, and this appears in fact to 
be the useful effect of loosening the soil by tillage which ex- 
poses it to the influence of the air. [Berzelius.] 

Lime. 

Berzelius thinks that lime and ashes act alike as converters 
of mould into soluble matters which serve as food to the plants. 
He thinks calcareous matters act also as stimuli to the plants. 

Dr. Dana considers the practice of mixing lime with peat as 
the worst that can be followed, as a compound is formed of little 
solubility, viz. geate of lime. He recommends the ley of wood- 
ashes, which gives a dark-brown solution, the alkaline proper- 
ties of the lime are neutralized and a large quantity of water 
is absorbed. See Report on Reexamination of the Geology of 
Massachusetts, 1838, pp. CO, 88. 



APPENDIX. 411 

Ammonia. 

Dr. Jackson is of opinion that the ammoniacal salts act in 
a different way from that stated by Liebig ; that the carbonate 
of ammonia acts upon the organic matters of the soil, and ren- 
ders the organic acids neutral and soluble ; decomposes and 
renders inert, noxious metallic salts and other compounds. 

Dr. Jackson objects that Liebig has not produced any in- 
stance where a plant has been raised by a solution or other 
preparation of ammonia in a purely siliceous or other pure 
earthy soil. This question is, therefore, open for research, and 
experiments have been instituted to decide it. (That ammonia 
in the state of carbonate and in solution in water has a great 
effect in stimulating plants, has long been known to gardeners, 
but they also well know that the plant so treated soon perishes. 
It would seem to be an analogous case to that of plants stimu- 
lated by chlorine, but not supplied with a proportionally in- 
creased allowance of food. — W.) 

Root Secretions, 

It should be stated that the accuracy of the experiments of 
Macaire-Princep adduced by the author, page 209, is not gen- 
erally admitted. Other chemists have been unable to obtain 
similar results, or if they do, are inclined to ascribe them to 
injury of the roots of the plants examined. Professor Lindley 
has in his notice of Liebig's work remarked that he has no fixed 
opinion on the subject, it being a question of facts and not of 
induction. Admitting root secretions, he nevertheless does not 
deem it necessary to look to the roots for these excretions, 
when we have so many proofs of their constant occurrence in 
other parts of a plant, as in the oily, resinous, waxy, acid and 
acrid matter, from various parts of their surface, and in the 
peculiar substances lodged in the hollows of their stems or else- 
where, such as Tabasheer, in the bamboo. These are thought 
to be instances "sufficient to satisfy the necessity of excretions 
occurring, and to render it superfluous to look to the roots for 
further aid in this particular." — W. 



412 APPENDIX. 

Phosphate of Lime. 

Dr. Dana has argued with great ability that phosphate of 
lime is a constituent of all soils in their natural state. " When 
we consider," he remarks, " that the bones of all graminivorous 
animals contain nearly 50 per cent, of phosphate of lime, we 
might be at liberty to infer the existence of this principle, in the 
food, and consequently, in the soil, on which these animals 
graze. If we look at the actual result of the analysis of beets, 
carrots, beans, peas, potatoes, asparagus, and cabbage, we find 
phosphate of lime, magnesia, and potash, varying from 0.04 to 
J .00 per cent, of the vegetable." — " Let us look at the extensive 
crops often raised where man has never manured. Rice, wheat, 
barley, rye, and oats, all contain notable portions of phosphate 
of lime, not only in the grain, but in the straw, and often in the 
state of superphosphates. The diseases, too, ergot and smut, 
show free phosphoric acid." — "Take, too, the cotton crop of 
our country. What vast quantities of phosphates do we thus 
annually draw from the soil ? Cotton gives one per cent, ashes, 
of which 17 per cent, is composed of phosphate of lime and 
magnesia. The like is true of tobacco. It contains 0.16 per 
cent, of phosphate of lime. The pollen of the piiius abies, 
wafted about in clouds, is composed of 3 per cent, of phosphate 
of lime and potash. May not this be one of nature's beautiful 
modes of supplying phosphoric acid to plants and soils ? If, as 
the late experiments of Peschier have proved, sulphate of lime, 
in powder, is decomposed by growing leaves, the lime liberated, 
and the sulphuric acid combining with the potash in the plant, 
why may not phosphate of lime, applied by pollen, act in the 
same way ?" Dr. Dana proceeds to state the amount of phos- 
phates in the ashes of different plants, which have been quoted 
at page ^28. Phosphate of iron, he continues, is common in 
turf; bog ore, and some barren and acid soils owe their acidity 
to free phosphoric acid. If we allow that our untouched forest 
soil contains phosphate of lime, it may be said, that this, being 
in small quantity, will be soon exhausted by cultivation, and 
that the phosphates, which we now find in cultivated fields, 
rescued from the forest, are due to our manure ; — I give you 
the general result of my analysis of cow dung, as the best argu- 



APPENDIX. 4 1 3 

ment in reply, — in such terms as the farmer may comprehend; 
water 83.60, hay 14, biliary matter (bile resin, bile fat, and 
green resin of hay) 1.275 ; geine combined with potash, (veg- 
etable extract) 0.95, albumen 0.175. 

" The hay is little more altered than by chewing. The albu- 
men has disappeared, but its green resin, wax, sulphate and phos- 
phate of lime remain, and when we take 100 parts of dung, 
among its earthy salts we get about 0.23 parts phosphate, 0.12 
carbonate, and 0.12 sulphate of lime. Now a bushel of green 
dung, as evacuated, weighs about 87.5 lbs. Of this, only 2.40 per 
cent, are soluble. Of tliis portion, only 0.95 can be considered 
as soluble geine." 



PEAT COMPOST. 

(page 231.) 



According to the statement of Messrs. Phinney and Hag- 
garston, as contained in the Report on the Geological and ^Igri- 
mllural Survey of Rhode Island, by Dr. C. T. Jackson, a compost 
made of three parts of peat and one of stable manure, is equal 
in value to its bulk of clean stable dung, and is more permanent 
in its eifects. 

Dr. Jackson deems it essential that animal matters of some 
kind should be mixed with the peat, to aid the decomposition and 
produce the requisite gases. Lime decomposes the peat, neu- 
tralizes the acids, and disengages the ammonia. The peat ab- 
sorbs the ammonia, and becomes in part soluble in water. The 
soluble matter, according to Dr. Jackson, is the apocrenate of 
ammonia ; crenate of ammonia, and crenate of lime being also 
dissolved. With an excess of animal matter and lime, free car- 
bonate of ammonia is formed. 

The peat should be laid down in layers with barn-yard manure, 
night soil, dead fish, or any other animal matter, and then each 
layer strewed with lime. In Dr. Jackson's report, he has presented 
highly valuable results from the use of this compost, which de- 
serves the attention of every agriculturist. He gives the follow- 
ing details of the manner in which the compost was prepared upon 
35* 



414 



APPENDIX. 



the farm of Mr. Sanford, near the village of Wickford in North 
Kingston. '• In the corner of tlie field a cleared and level spot 
was rolled down smooth and hard, and the swamp muck was 
spread upon it, forming a bed eight feet wide, about fifteen or 
twenty feet long, and nine inches thick. For every wagon load 
of the muck one barrel of fish was added, and the fish were 
spread on the surface of the muck, and allowed to become pu- 
trescent. The moment they began to decompose, he again cov- 
ered them with peat, and a renewed layer offish was spread and 
covered in the same manner. The fermentation was allowed to 
proceed for two or three weeks, when the compost was found to 
have become fit for the land. To this he was advised to add lime 
in the proportion of one cask to each load of compost early in the 
spring, which it was supposed would complete the decomposition 
in two or three weeks. Such a heap should be rounded up and 
covered, so as to prevent the rain washing out the valuable salts, 
that form in it. And in case of the escape of much ammonia, 
more swamp muck or peat should be spread upon the heap, for 
the purpose of absorbing it. Dr. Jackson is of opinion that the 
phosphoric acid of the peat and animal matter would convert the 
lime into a phosphate, and thus approximate it very closely to 
bone manure." — Report, p. 170. 

Any refuse animal matter can be, of course, employed in a 
similar manner. " The carcase of a dead horse, which is often 
suff'ered to pollute the air by its noxious effluvia, has been 
happily employed in decomposing 20 tons of peat earth, and 
transforming it into the most enriching manure." — Young's Let- 
ters of ^gricola,Lietter 25, p. 238.* 

Night soil may be composted with peat with great advantage, 
sufficient lime being added to deprive it of odor; large quanti- 
ties of ammonia are given off and absorbed.f 

* In a Report on a Reexamination of the Geology of Massachu- 
setts, J 838, Dr. Dana particularly notices the evohition of ammonia 
from fermenting dung, and supposes that the ammonia combines with 
geine to form a soluble compound. Sec JS'otc to page 83 of the Re- 
port. 

t JVight Soil. The quantity of night soil collected and removed from 
the city of Boston annually, is about four hundred thousand square feet. 



APPENDIX. 415 

Appended to Dr. Jackson's report will be found a letter from 
E. Phinney, Esq., of Lexington, well known as one of the most 
skilful agriculturists, On the reclaiming of peat bogs and the em- 
ployment of peat as manure. 



COLLECTION AND USE OF MANURE IN CHINA. 

(Extract from the communication referred to at page 242.) 

" Human urine is, if possible, more husbanded by the Chinese 
than night soil for manure ; every farm, or patch of land for cul- 
tivation, has a tank where all substances convertible into manure 
are carefully deposited, the whole made liquid by adding urine 
in the proportion required, and invariably applied to the soil in 
that state. The business of collecting urine and night soil 
employs an immense number of persons, who deposit tubs in 
every house in the cities for the reception of the urine of the in- 
mates, which vessels are removed daily with as much care as our 
farmers remove their honey from the hives. The night soil is 
collected in the same way, as well as on the roads and by- 
places, persons being always on the alert with baskets and 
rakes to avail of the least particle that appears. The Chinese 
get as much off their land, as it is capable of producing, and this 
is done by the liberal use of manure, and application of much 
more labor in working the soil than in other countries. The reason 
they do not use dung is, that they have comparatively no animals; 
horses and cattle are so rare, that every thing except plough- 
ing, which is done with the buffalo, is accomplished by manual 
labor." 

It is used by cultivators in the immediate vicinity, being composted 
with soil, lime, peat, &c. Large quantities of animal matter from 
slaughter houses, and other sources, are also made use of. The heaps 
are left exposed, uncovered to the air, and the value of the compost is 
consequently greatly diminished. See page 242. 



416 APPENDIX. 

ADDITION TO NOTE AT PAGE 70. 

If the atmosphere possessed, in its whole extent, the same 
density as it does on the surface of the sea, it would have a 
height of 24.555 Parisian feet ; but it contains the vapor of 
water, so that we may assume its height to be one geographical 
mile = 22,843 Parisian feet. Now, the radius of the earth is 
equal to 860 geographical miles ; hence the 

Volume of the atmosphere =9,307,500 cubic miles = cube of 210.4 

miles. 
Volume of oxygen = 1,954,578 cubic miles =cube of 125.0 miles. 
Volume of carbonic acid = 3,862.7 cubic miles = cube of 15.7 miles. 

The maximum of the carbonic acid contained in the atmo- 
sphere has not been here adopted, but the mean, which is equal 
to 0.000415. 

A man daily consumes 45,000 cubic inches (Parisian). 

A man yearly consumes 9505.2 cubic feet. 

1,000 million men yearly consume 9,505,200,000,000 cubic 
feet. 

1 cubic mile is equal to 11,919,500,000,000 cubic feet. 

Hence a thousand million men yearly consume 0.79745 cubic 
miles of oxygen. But the air is rendered incapable of support- 
ing the process of respiration, when the quantity of its oxygen is 
decreased 12 per cent. ; so that a thousand million men would 
make the air unfit for respiration in a million years. The con- 
sumption of oxygen by animals, and by the process of combus- 
tion, is not introduced into the calculation. 



TABLES 



SHOWING THE PROPORTION BETWEEN THE HESSIAN AND ENG- 
LISH STANDARD OF WEIGHTS AND MEASURES. 

As the numbers throughout the work have been stated in ref- 
erence to some common measure, it has been thought advisable 
not to state the English equivalents to the Hessian numbers in 
the text, lest they should distract the attention of the reader by 



APPENDIX. 417 

being placed in decimals. The numbers do not represent abso- 
lute quantities, but are merely intended to denote a proportion to 
other numbers ; so that it is quite indifferent in what standard of 
weights or measures they are stated. In almost every case where 
the term " Hessian pounds," is employed, the word " parts " 
may be substituted. For those, however, who wish to be ac- 
quainted with the exact English quantities, a table is given be- 
low. 

1 lb. English is equal to 0.90719 lbs. Hessian ; hence about 
one tenth less than the latter. 



2 lbs 


1. Hessian are equal to 


2.20 lbs. 


English. 


3 


(c 


(( 


3.306 


(( 


4 


<( 


« 


4.409 


« 


5 


i( 


(( 


5.51 


tt 


6 


(( 


<< 


6.61 


tt 


7 


(1 


« 


7.716 


<< 


8 


(( 


ct 


8.818 


<( 


9 


(< 


tl 


9.92 


tt 


10 


tt 


« 


11.02 


tt 


20 


(( 


« 


22.04 


" 


30 


<( 


« 


33.06 


c< 


40 


(( 


« 


44.09 


(( 


50 


(( 


« 


55.11 


" 


60 


(1 


(( 


66.12 


(( 


70 


C( 


<( 


77.16 


(( 


80 


(( 


« 


88.18 


" 


90 


<1 


<c 


99.29 


ti 


100 


11 


(( 


110.2 


tl 


200 


t( 


(( 


220.4 


ti 


300 


<( 


(l 


330.6 


" 


400 


<( 


a 


440.9 


it 


500 


(( 


it 


551.1 


ti 


600 


(( 


tt 


661.2 


tl 


700 


(( 


It 


771.6 


11 


800 


(( 


tt 


881.8 


" 


900 


It 


tt 


992.9 


tl 


[000 


« 


(( 


1102.0 


u 



418 



APPENDIX, 



SQUARE FEET. 

The Hessian acre is equal to 40,000 Hessian square feet, or 
26,917 English square feet ; one English square foot being equal 
to 1.4864 Hessian. The following is a Table to save the trouble 
of calculation. The Table is only stated to the figure 10, but by 
removing the decimal point one or two figures, the whole series 
given in the case of the pounds will also be obtained. 

2 square feet Hessian are equal to 1.345 square feet English. 



3 




2.011 


4 




2.691 


5 




3 363 


6 




4.036 


7 




4.709 


8 




5.382 


9 




6.054 


10 




6.727 




CUBIC 


FEET. 



One English cubic foot contains 1.81218 of a Hessian cubic 
foot ; the Hessian and English cubic inch may be considered as 
equal, one English cubic inch containing 1.048715 Hessian cu- 
bic inch. 



1 cubic foot Hessian is equal to 0.551 cubic foot English. 

2 feet " " 

3 «' " 



4 
5 
6 

7 

8 

9 

10 



1.103 
1.655 
2.207 
2.759 
3.311 
3.863 
4.415 
4.966 
5.518 



feet 



APPENDIX. 



419 



TABLE OF THE CORRESPONDING DEGREES ON THE SCALES OF 
FAHRENHEIT, REAUMUR, AND CELSIUS, OR CENTIGRADE. 







6 




3 

Pi 






3 
nJ 




212 


80 


100 


149 


52 


65 


50 


8 


10 


203 


76 


95 


140 


48 


60 


41 


4 


5 


194 


72 


90 


131 


44 


55 


32 








185 


68 


85 


122 


40 


50 


23 


— 4 


— 5 


176 64 


80 


113 


36 


45 


14 


— 8 


— 10 


167 60 


75 


104 


32 


40 


5 


— 12 


— 15 


158 


56 


70 


95 


28 


35 


4 


— 16 


— 20 








86 


24 


30 


— 13* 


— 20 


— 25 








77 


20 


25 


— 22 


— 24 


— 30 








68 


16 [20 


— 31 


— 28 


— 35 








59 


12 15 


— 40 


— 32 


— 40 



— Denotes below the cipher on Fahrenheit's scale. 



INDEX. 



ACI 
Absolute weight, 3. 

Jlbsorpd'jn by roots, 147. 

of salts, 157. 
Acid, acetic, 95. 

emitted by plants, 194. 

transformation of, 267. 

formation of, 293 - 297. 

apocrenic, 5d. 

benzoic, 138. 

boracic, 164. 

carbonic, 70. 

decomposed by plants, 

73. 

injurious to plants, 119. 

from respiration, 71. 

why necessary to plants, 

147. 

crenic, 58. 

cyanic, transformation of, 271. 

formic, 112, 127,251. 

hippuric, 138. 

humic, 60. 

properties of, 63. 

hydrocyanic, 110, 251. 

hyponitrous, 55. 

kiiiic, 155. 

lactic, 236. 

production of, 284. 

nieconic, 155, 

melanic, 289. 

mellitic, 104. 

nitric, 55. 

source of, 129. 

organic, action of upon car- 
bonate of silver, 256. 

phosphoric, in ashes of plants, 
200. 

rocellic, in plants, 149. 

silicic, 215. 

succinic, 104. 

sulphuric, action of on soils, 
247. 

36 



ALD 

Acid, tartaric in grapes, 149. 
Acids, what, 13. 

action of upon sugar, 264. 

arrest decay, 338. 

equivalents of, 35. 

organic, in plants, 55, 148. 

when formed, 80. 

oxygen, .35. 

retard decay, 102. 

saturating power of, 47. 
Acid salts, 48. 
Adipocire, 129. 
Affinity, 6, 15, 109. 

action of, 7. 

chemical, examples of, 253. 

increase of, 23. 

predisposing, 24. 

weak, example of, 254. 
Agave Americana, absorbs oxvffen, 

80. ^^ 

Agriculture in China, 240. 

object of, 141, 189,217. 

• how attained, 189. 

its importance, 187. 

a principle in, 233. 
Air, access of, favored, 106. 

carbon in the, 72. 

carbonic acid in, 71. 

decomposed by plants, 

72. 

quantity extracted, 75. 

effect of upon juices, 293. 

from decay of woody fibre, 
95. 

improved by plants, 77. 

necessary to plants, 172. 
Albumen, 137. 
Alcohol, effect of heat on, 267. 

exhaled, 113. 

products of its oxidation, 290. 

from sugar, 275. 
Aldehyde, 290. 



AMM 



422 



ASH 



Alkalies, 14,50, 110, 

evolve nitrogen, 270. 

from granite soils, 158. 

presence of indicated, 198. 

promote decay of wood, 102. 

quantity removed from air, 
1G2. 

in aluminous minerals, 

192. 
Alkaline bases, in plants, on what 
their existence depends, 153. 
* salts in plants, sources of, 195. 
Mkargen, 342. 
Alloxan, 319. 
Alloxantin, 320. 
Almonds, bitter, oil of, 2S8. 
Alternation of crops, advantages of, 
214. 

produces humus, 217. 
AlthecB, 93. 
Alumina, in fertile soils, 191. 

its influence on vegetation,191. 
Amber, origin of, 104. 
Ammonia, carbonate of, from urine, 
237. 

how fi.Ked, 238. 

cause of nitrification, 303. 

changes colors, 128. 

condensed by charcoal, 146. 

conversion of into nitric acid, 
301. 

decomposed by gypsum, 142. 

by manganese, &c., 301. 

detected, 132,238. 

early existence of, 165. 

fixed by gypsum, 142. 

from animals, 219. 

beet root, «&c., 135. 

hydrocyanic acid, 111. 

maple juice, 134. 

stables, 239. 

furnishes nitrogen, 146. 

liberated, 270. 

loss from evaporation, 246. 

most stable compound of ni- 
trogen, 270. 

neutralized, 375. 

nitrate of formed, 301. 

not formed on cultivated land, 
217. 

produced by animal organism, 
165. 

product of decay, 129. 

of disease, 374. 

properties of, 127 

quantity absorbed by charcoal, 
146. 



Ammonia, quantity absorbed by de- 
cayed wood, 146. 

in rain water, 130 - 132. 

separated by rain, 146. 

in snow water, 132. 

solubility of, 130. 

transformation of, 127. 

water from, 302. 
Ammoniacal salts, their mode of ac- 
tion, 411. 
Amylin, its effect, 114. 
Analysis of decayed wood. 326. 

of fire damp, 334. 

of oak wood, 99, 100. 

of salt water, 166. 

of soils by Berzelius, 409. 
Animal food, preservation of, 294. 

life, connexion of, with plants, 
73. 

bodies, decay of, product of 
the, 129. 
Animals, analysis of their bones, 203. 

elements that support, 147. 

excrements of, 139, 220. 

fattening of, 190. 

whence they derive phospho- 
ric acid, 201. 

concretions in, 201. 

putrefaction of, 219. 
Animal excrement, its chemical na- 
ture, 220. 

manuie, 410. 
Annual plants, how nourished, 178. 
Antkuxanthum odoratum, acid in, 

139. 
Anthi acite, 334. 
Antidotes to poisons, 343. 
Apatite, 201. 
Apotkeme, 57. 

quantity in wheat, 58. 
Appcrt's method of preserving, 318. 
Aqiiic fortis, 55. 
Arable land, 190. 

Aromatics, their influence on fer- 
mentation, 309. 
Argillaceous earth, its origin, 191. 
Arragonitc, transformation of, 258. 
Arsenious acid, action of, 241. 
Ashes, as manure, 227. 

phosphates in, 412. 

comparative value of, 228. 

of fire wood, 64. 

of pine trees, 151. 

of plants, origin of salt in, 166. 

importance of examination of, 
153. 

of wheat, 203. 



BEE 



423 



BUT 



Ashes, of bones, 227. 

of peat, 230. 
Assimilation of carbon, 77-85. 

of carbonic acid and ammo- 
nia, 174. 

of hydrogen, 120. 

of nitrogen, 126. 

most active in woody fibre, 
148. 

requires nitrogen, 181. 

its power, 184. 
Atmosphere, composition of, 55. 

how maintained, 74 - 76. 

proportion is invariable, 70. 

carbonic acid in, 74. 

moisture to plants from, 118. 

motion of, 76. 

nitrogen from, 129. 

oxj'gen given to by land, 121. 
Atovis, motion of, 257. 

permanence in position of, 
258. 
Atomic theory, 38. 
Attraction, 2. 

chemical, 4. 

powerful, overcome, 271. 
Azores, springs containing silica, 215. 
Azotized matter in juices of plants, 
181. 

substances, combustion of, 
299. 

formation of nitrates without, 
302. 

Balance, 3. 

Bamboo, silica in, 216. 

Barilla, 160. 

£arA; of trees, products in, 78. 

Barley, analysis of, 199. 

Barruel, his experiments on blood, 

368. 
Base, what, 110. 

Bases, alkaline in plants, on what 
their existence depends, 
153. 

organic, 56. 

oxygen, 35. 

in plants, 148. 

substitution of, 149. 
Basic salts, 47. 
Beans, alkalies in, 204. 

nutritive power of, 204. 
Becquerel, experiments of, 194. 
Beech, ashes of, 228. 
Beer, 309. 

Bavarian, 314. 

varieties of, 314. 



Beet root sugar, 67. 

ammonia from, 135. 

from sandy soil, 184. 
Benignant disease, 368. 
Benzoic acid, 138. 

formed, 288. 
Benzule, 138. 
Bergstrasse, 171. 
Berzelius, his discovery of crenic 

acid, «&c., 58. 

his analysis of faeces, 225. 

of soils, 409. 

on mode of action of lime, 
410. 
Binary compounds, 13. 
Binoxide of nitrogen, 55. 
Birch tree, ammonia from, 135. 
Bleaching salts, 143. 
Blood, its office, 178. 

action of chemical agents up- 
on, 361. 

its feeble resistance to exte- 
rior influences, 360. 

organic salts in, 337. 

its character, 349. 
Blossoms, when produced, 108. 

increased, 175. 

removal of from potatoes, 177. 
Bodies, amorphous, 18. 

compound, 13. 

condition of, changed, 259. 

decomposition of, 25. 

containing nitrogen, transfor- 
mation of, 266 - 269. 

gaseous, union of, 39. 

properties of, 8. 

simple, 12. 

weight and volume of, 41. 
Body, defined, 1. 
Bones, analysis of, 202. 

durabihty of, 246. 

gelatine in, 246. 
Bone ashes, 227, 

manure, 229. 
Bouquet of wines, 311. 
Boracic acid, 164. 
Botanists, neglect of chemistry by, 

85. 
Brandy from corn, 308. 

oil of, 310. 
Brazil, wheat in, 198. 
Bread from wood, 175. 
Broion coal, 325. 

ashes of, 230. 
Buckwheat, ashes of, 204. 
Bulbs, how nourished, 117. 
Butter, contains hydrogen, &c., 91. 



CAR 



424 



COA 



Calcareous SPAR, 258. 

Calcium, fluoride of, 202. 
Calculous disorders, 115. 
Calico printing, use of cow dung in, 

232. 
Caloric, 9. 

Caoutchouc in plants, 118. 
Carbon, 54. 

absorbed by roots, 75. 

afforded to the soil by plants, 
116. 

assimilation of, 57, 77, 85. 

combination of, with oxygen, 
2ti7. 

of decaying substances, sel- 
dom affected by oxygen, 
286. 

derived from air, 72, 74. 

in decaying wood, 100. 

in decayed woody fibre, 77. 

in sea- water, 74. 

oxide of, formed, 267. 

quantity in grain, «fec., 67. 

in land, 68. 

in straw, CD. 

restored to the soil, 116. 

received by leaves, 75. 

in sugar, 275. 

its affinity for oxygen, 291. 
Carbonate of ammonia decomposed 
by gypsum, 142. 

lime in caverns and vaults, 
169. 

from urine, 237. 

how fixed, 238. 
Carbonic acid changes in leaves, 186. 

in air, 71,74, 167. 

decomposed by plants, 72, 186. 

effect of, on corn, 119. 

emission of, at night, 83. 

from the earth, 173. 

evaporation of, 84. 

its evolution from decay of 
bodies, 292. 

from decaying plants, 126. 

respiration, 113. 

excrements, 140. 

humus, 117. 

springs, 126. 

woody fibre, 95. 

increase of, prevented, 71. 

influence of light on its de- 
composition, 83. 

transformation of, 186. 

quantity from air, 75. 

in springs, 330. 

in water, decomposed, 85. 



Carbonic acid, nutrition of plants by, 
87. 

source of, 105. 

when injurious, 119. 
Carburetted hydrogen with coal, 333. 
Catalyctic force, 44. 

objections to, 45. 
Catahjlism, 42, 44. 
Caverns, stalactites in, 170. 
Charcoal, condenses ammonia, 146. 

experiments of Lukas and 
Buchner, 119. 

may replace humus, 119. 

theory of its action, 119. 

promotes growth of plants, 
247. 

spontaneous combustion of, 
287. 
Chemical attraction, 4. 

affinity, 380. 

effects of light, 185. 

forces can replace the vital 
principle, 11-5. 

processes in nutrition of veg- 
etables, 53. 

properties of bodies, 8. 

proportion, laws of, 32. 

transformations, 109, 249. 
Chemist, his duly, 190. 
Chemistry, organic, what, 53. 

neglected by botanists, 85. 

and physiologists, 86. 

Chinese, manure collected by the, 
240. 

and prepared, 241. 

China, its agriculture, 240. 

collection and use of manure 
in, 415. 
Chlorine, its effect, 143. 

decomposes water, 184. 

salts, 50. 

and hydrogen, 185. 
Chloride, what, 13. 

of calcium, 143. 

of nitrogen, 254. 

of potassium, its effect, 156. 
Cinchona, acid in, 155. 
Clay, as manure, 144. 

burned, advantages of, as ma- 
nure, 144. 
Clays, potash in, 192. 
Clay slate, 202. 
Coal, formation of, 325. 

plants in, 117. 

inflammable gases from, 333. 

origin of substances in, 104. 

of humus, 57, 172. 



CRO 



425 



DEN 



Coal, wood, 327. 
Cohesion, 4. 

of fluids and gases, 5. 

influence of, 22. 
Colors of flowers, 13ri. 
Combinalion, chemical, 24, 22, 109. 

influenced, 23. 
Combinations tliat undergo fermen- 
tation and putrefaction, 265. 
Combining-pi-oportions, 121. 
Combustion, 7. 

removes oxygen, 72. 

at low temperatures, 291 . 

of decayed wood, 103. 

induction of, 296. 

spontaneous, 287. 
Composition, chemical, connexion 

of, with form, 42. 
Compost, for grass, 160. 

of peat, 160. 
Compounds, binary, 13. 

classes of, l3. 

new, how produced, 212. 

organic, composition of, 123. 

triple, decomposition of, 31. 

conditions for forming, 22. 
Cold meat, its state, &c., 369. 
Concretions from horses, 201. 
Constituents of plants, 202. 

what, 7. 

ultimate, 13. 
Contagion, reproduction of, on what 
dependent, 370. 

susceptibility to, how occa- 
sioned, 369. 
Contagions, 335. 

propagation of, 363. 
Contagious matters, action of, 363. 

their effects explained, 353. 

life in, disproved, 361. 

reproduction of, 366. 
Copper, alloy of, its action on sul- 
phuric acid, 253. 
Corn brandy, 308. 

how cultivated in Italy, 197. 

phosphate of magnesia in, 
200. 
Corrosive sublvmate, its use, 102. 

action of, 341. 
Cow, excrement of, 221. 

urine of, 222. 

rich in potash, 244. 

Coto pox, action of vims of, 371, 
Crops, interchange of, 206. 

favorable effect of; 208. 

causes, 2l4. 



Crops, principles regulating, 219. 
Crystals, what, 15. 

obtained, 17. 

increased, 19. 

isomorphous, 18. 
Crystallization, 15. 

water of, 20. 
Cultivation, its benefits, 77. 

different methods of, 188. 

object of, 141, 105. 
Culture, art of, 169. 

of plants, principles of the, 
189. 
Cyanic acid, transformation of, 271. 
Cyanogen, 110. 

combustion of, 300. 

transformation of, 272. 

D^NA, Dr. S. L., on geine, 59. 
on the decay of plants, 96. 
on phosphates in soil, 228. 
on the existence of phosphate 

of lime in soils, 4l2. 
on the action of lime, 410. 
on evolution of ammonia, 
414. 
Davis, his account of Chinese ma- 
nure, 241. 
Daubeny, Professor, his theory of 
origin of ammonia, in 
springs, 133. 
Death from nutritious substances, 90. 
the source of life, 147. 
of animals, changes produced 
by, 219. 
DecandoUe, his theory of excretion, 
2(17. 
difference between his views 
and those of Macaire-Prin- 
cep, 212. 
Decay, 95, 2(i0. 

a source of ammonia, 129. 
of wood, 96, 101. 

promoted, 102. 

of plants restores oxygen, 125. 
and putrefaction, 252. 
Decomposing body, its effect, 348. 
Decomposition, 25, 109, 249. 
organic chemical, 251. 
partial, 26. 
influenced, 29. 
of triple compounds, 31. 
results of, influenced, 299. 
of wood, 327. 
Decrepitation, 18. 
Density, 2. 



36* 



ESP 



42G 



FLE 



Derbyshire spar, 202. 

De Saussure, his experiments, 79. 

28!), 2'JG. 
Development of plants, 187. 
Dextrine, 87. 
Diamond, 54. 

its origin, 104. 
Diastase, 17!/, 378. 

contains nitrogen, 180. 
Digestion and assimilation, 182. 
Disease, how excited, 3G4, 367. 
Diseases of trees, 181. 
Dissection, wounds received in, 350. 
Distillation, dry, 284. 
Z)oo-, excrement of the, 220. 
Double salts, 47. 
Dry distillation, 284. 
Ductile bodies, 5. 
Dung reservoirs, 237. 

analysis of, 413. 

hills, liquid from, 238. 

EARTHS, 5\. 

Ebony wood, oxygen and hydrogen 

in, 82. 
Effete matters, separated, 109. 
Efflorescence, 20. 
Eggs, development of, 180. 
Elasticity, 5. 
Electrical action, 253. 
Elements, 12. 

of plants, 53. 

not generated by organs, 90. 

supporting animals, 147. 

their source, how known, 94. 
Elms, excretions of, 78. 
Enamel of teeth, 203. 
Equilibrium of attractions disturbed, 

2G6. 
Equivalent, its meaning, 34, 121. 
EquisetacecE contain silica, 216. 
Eremacausis, 95, 259, 285. 

arrested, 286. 

conditions for, 285, 296. 

analogous to putrefaction, 292. 

differs from putrefaction, 302. 

of bodies destitute of nitrogen, 
293, 

necessary to nitrification, 303. 

substances that undergo it, 
287. 

of bodies containing nitrogen, 
299. 
Erfurt, quantity of raiu at, 65. 
Ergot and smut, 412. 
Esparsette, cultivation of, its advan- 
tage, 217. 



Ether, cenanthic, 306, 
Eudiometer, 131. 

Excrementitious matter, composition! 
of, various, 1 13. 

production of, illustrated, 112. 
Excrement, animal, its chemical na- 
ture, 220. 

of the dog, cow, &c., 221. 

influence of, as manure, 225. 
Excrements, animal, 207, 211. 

of plants, 211. 

conversion of, into humus,214. 

of man, amount of, 242. 

value of, 235. 

preparation of, 243. 
Excretion, organs of, 113. 
Exciter, its effect, 3-18. 
Excretions of elms, &c., 78. 

of plants, theory of, 207. 
Experiments in physiology, object of, 
88. 

of physiologists, not satisfac- 
tory, 92. 
Extract of humus, 57. 

FALLOW, changes from, 197. 

crops, 204. 

time, 204. 
Fattening of animals, 190. 
Faces, analysis of, 225. 
Ferment, 277, 'M)A. 
Fermentation, 95, 259, 261. 

of Bavarian beer, 316. 

of beer, 214. 

cause of, 261, 282. 

Gay-Lussac's experiments, 
294. 

of sugar, 275. 

results of, 274. 

of veijetable juices, 276. 

how excited, 279. 

vinous, 303. 

of wort, 30.5. 
Fertility of fields, ho w preserved, 226. 

increased, 173. 

diminished, 196. 
Fibril, radical, how regarded, 105. 
Fibrine, 222. 

Ficus JIustralis, growth of, 383. 
Fire of London, plants after it, 199. 
Fire-dump, 333. 

Fir-ioood, analysis of its ashes, 152. 
Fishes in salt pans, 163. 
Flandirs, manure used in, 240. 
Fleabane, 205. 
Flesh, analysis of, 222. 

effect of salt on, 338. 



GRA 



427 



HUM 



Flour, bran of, 148. 

Flowers, colors of, due to ammonia, 

133. 
Fluid, defined, 1. 
Fluorides, 202. 
Fluorine, 202. 

salts of, 50. 
Food, effect of too great supply of, 
90. 
effect on products of plants, 

183. 
its influence, 187. 
of plants, 180. 
. how received, 104. 
of young plants, 174. 
transformation and assimila- 
tion of, 113. 
Form, external, connexion of, with 

composition, 42. 
Formation of wood , 181 . 
Formic acid, 111. 

theory of its formation, 112, 

2.51. 
from hydrocyanic acid, 273. 
Formula for elements of wood, 101. 
Fossil resin, origin of, 104. 
France, preparation of excrements in, 

243. 
Franconia, caverns in, 170. 
Fruit increased, 175. 

ripening of, 124. 

changes attending, 175. 

Fulminating silver, 254. 

compounds, effect of motion, 
&c., on, 379. 
Fusing point, 11. 

GjiSEOUS substances in the luncrs, 

effect of, 373. 
Gasterosteus aculeatus in salt pans, 

163. 
Gay-Lussac, his experiments, 294. 
Geraniums, effects of chlorine on, 
143. 
soil for, 143. 
Germany, cultivation in, 226. 
Germination of potatoes, 176. 

of grain, 179. 
Glass, as rnanuie, 233. 
Glue, manure from, 230. 
Gluten, conversion of, into yeast, 319 
-348. 
decomposition of, 283,304. 
gas fioin, 3(i4 
Grain, germination of, 179. 

harvest of, in Germany, 160. 
manure for, 160. 



Granite soil, affords alkalies, 153. 
Grapes, compost for, 160. 

constituents of the seeds, 148. 

fermentation of their iuice, 
294. 

juice of, differences in, 312. 

polash in, 153. 
Grasses, seeds of, follow man, 162. 

silica in, 158. 

valued in Germany, 159. 
Grauwack^, soil from, 191 
Green principle of leaves, 218. 
Growth of plants, conditions for the, 
188. 

without mould, 383. 
Guano, 244. 
Gwm, influence of, on development of 

plants, 177. 
Gypsum, decomposition of, 144, 282. 

its influence, 142. 

use of, 238. 

H^MATIN, 289. 

Haggerston, Mr., his compost, 160. 

HaUiydrates, 48. 

Haloid salts, 59. 

Hard icater rendered soft, 133. 

Hay, carbon in, 67. 

composition of, 67. 

contains nitrogen, 222. 

silica in, 200. 
Haystack, effect of lightning upon, 

200. 
Heat, action of, 9. 

free, 11. 

specific, 12. 
Hermann, his analysis of humic acid, 

409. 
Hessian and En<rlishfeet, 418. 

cubic feet, 418. 

Hcteromorphuus crystals. 17. 
Hibernating animals, 177. 
H'ppuric acid, 138. 
Hitchcock, Professor, his table of 

geine in soils, 59. 
Honey dew, 181. 
Horse, urine of, 143. 

carcase of, its use, 414. 
Horses, concretions in, 201. 
Horse-chestnut, excretions of, 78. 
Horse-dunif, action of water upon, 
223. 

analysis of, 223. 
Humanfaces, analysis of, 225 
Humute of time, quantity received by 

plants, 66. 
Humic acid, 57, 60. 



INS 



428 



LIG 



Hiimic acid, action of, 171. 

properties of, 63. 

in wheat, 65. 

quantity received by plants, 
Go. 

its nutritive office, 66. 

in excretions of oaks, &c., 78 

insolubility of, 170. 
Humic extract, 62. 

acid, analysis of, 409. 
Ilumin, ^)7. 
Humus, 57, 96. 

action of, 106. 

erroneous opinion of, 78. 

action upon oxygen, 170. 

coal of, 57, 172. 

conversion of woody fibre in- 
to, 98. 

how produced, 99. 

its insolubility, 169. 

nourishes plants, 174. 

origin of, 95. 

properties of, 62. 

replaced by charcoal, 118. 

source of carbonic acid, 117. 

sources of, 117. 

theory of its action, 119. 

when soluble, 169. 

unnecessary, 174. 

Hyacinth, colored, 156. 
Hyilrates, what, 48, 60. 
Hydrocyanic acid, 110, 251. 

decomposition of, 111, 251. 

various substances from. 111. 
Hydrogen, assimilation of, 120. 

excess in wood accounted for, 
121. 

of decayed wood, 103. 

of plants, source of, 122. 

in oak and other woods, 82 

influence of, upon plants, 79. 

peroxide of, 254. 

of sugar, 276. 
Hydrogen and oxygen, union of, 41. 

ICE, bubbles of gas in, 84. 
Imponderables, 2. 
Indifferent substances, 56. 
Indifferent organic compounds, 375. 
Infusorial vegetables in peat, &c., 215. 
Ingenhouss, his experiments, 79. 
Inorganic compounds, 262. 

action of, 335. 

in wliat they differ from or- 
ganic, 263. 
Inorganic constituents of plants, 147. 
Insoluble geine, 59. 



Interchange of crops, 206. 

prmciples regulating the, 219. 
Iodine, 168. 
Iron, oxide of, attracts ammonia, 145. 

pyrites in coal, 332. 
Irrigation of meadows, effect of, 169, 

214. 
Isomorphism, 42. 
Isomorphous crystals, 18. 
Itch insect, 1G3. 

JjiCKSON, Dr. C. T., his analysis of 
horse dung, 224. 
of peat, 231. 

his views of the action of am- 
monia, 411. 

Juices of plants, azote in, 181. 
effect of air upon, 293. 

KINIC ACID, 155. 

Lactic acid, production of, 277. 

Lamp-black, 2d7. 
Land, carbon in, 68, 

oxygen from, 121. 
La Place, law proposed by, 347. 
Lava, soil from, 194. 
Laws of chemical proportions, 32. 

decomposition, 26. 
Lead, salts of, compounds of with 
organic matters, .345. 
white, effects of, 345. 
Leaves, absorb carbonic acid, 72. 

aslies of contain alkalies, 198. 
cessation of their functions, 

108. 
change of color from absorp- 
tion of oxygen, 81. 
consequence of the production 
of their green principle, 218. 
decompose carbonic acid, 186. 
how regarded by physiolo- 
gists, 87. 
their office, 179. 
power of absorbing nutriment, 

how increased, 107. 
quantity of carbon received 

by, 75. 
contain azotized matter, 234. 
Lemonade, sulphuric acid, use of, 345. 
Liebig, his application of the term 

base, llo. 
Life, notion of, 356. 
Light, absence of, its effect, 79, 184. 
chemical, effects of, 185. 
cffi'ct of upon salts of silver, 
345. 



MET 



429 



NIT 



Light, influences decomposition of 

carbonic acid, 83. 
Lightning, its eflect on hay, 200. 
Lime, phosphate of, in roots, 93. 

in forest soil of U. S., 

228. 
Berzelius's opinion on its 
mode of action, 410. 

Dr. Dana's, 410. 

Lindley, Professor, his remarlcs on 

root secretions, 411. 
Linen, changes in, 326. 
Liquid, supposed decay in a, 104. 
Liverwort, acids in, 149. 
Lucern, phosphate of lime in, 204. 
benefits of its culture, 217. 

MacMRE-PRINCEP, his experi- 
ments, 2<)8. 
Magnesia, phosphate of in seeds, 93. 
Malic acid, its composition, 123. 
Malignant disease, 3(j8. 
Manure, 206. 

animal, yields ammonia, 136. 

best for plants, 172. 

carbonic acid from, 140. 

components of should be 
known, 188. 

animal, 410. 

use of in China, 415. 

of the Chinese, 240. 

effect of, 219. 

for grain in Germany, 160. 

nitrogen from, 140. 

strong, use of, 161. 

-water, its effect, 143. 

from fish, «fcc , 414. 
Manuring with lone, 229. 

with clay, 144. 
Maple juice, ammonia from, 134. 

trees, sugar of, 180. 
Mail, substance mistaken for, 215. 
Mask, 308. 
Matter, what, 1. 

particles of, 262. 
Meadow land, soil of, 159. 

geine in, 59. 

hay from, 159. 

observation of a, its value, 94. 
Meadows, irrigation of, 169. 
Meconic acid, 155. 
Medicine, action of remedies in, 234. 

may act as poison, 360. 
Melanic acid, 289. 
Mcllitic acid, 104. 

Metallic compounds required by 
plants, 90. 



Metallic oxides in fir-wood, 64. 
Metalloids, 13. 

Metals, power acquired by, 265. 
Metamorphosis, 1 12, 252. 
Miasm, defined, 373. 
Miasms, 335. 

most pernicious, 375. 
Milk, use of knowledge of its com- 
position, 91. 
Minerals, attract ammonia, 145. 
Mould, vegetable, 97. 

conversion of woody 

fibre into, 98, 105. 
Moisture, its effect on wood, 99. 
Molecules, different positions of, 258. 

motion of, 347. 
Morbid poisons, 352. 
Mother-ley, 19. 
Motion, its influence on chemical 

forces, 257. 
Mouldering of bodies, 325. 
Muriatic acid, formed, 185. 
Muscles in fish ponds, 164. 
Muscle, animal, analysis of, 222. 
Alust, fermentation of, 306. 

J^TaPLES, soil of, 197. 
JVarcotine, 155. 
Kascent slate, 23. 
Neutral salts, 35. 

state, 14. 
Nicotine, 311. 
Night soil, 414. 
NUe, soil of its vicinity, 214. 
Nitrates in plants, 138. 
Nitrate of silver, action of salt on, 

345. 
Nitric acid, 55. 

action of on starch, 86. 

from ammonia, 129, 301. 

animals, 129. 

formed, 299. 
Nitric oxide, 55. 
Nitrification, 95. 

condition for, 302. 

eremacausis not necessary to, 
303. 
Nitrogen, from animals, 129. 

application of substances con- 
taining it, 140. 

assimilation of, 126. 

binoxide of, 55. 

chloride of, 254. 

compounds of, 55. 

peculiarity in them, 282. 

deficient in excrements, why, 
140. 



ORG 



430 



PHO 



Mtrogen, described, 55. 

difficulties of determininff, 
301. ^ 

eliminated, 113. 

in excrements, 240. 

from the atmosphere, 129. 

in grass, 144. 

in hay, 222 

influence of upon plants, 7i). 

in lichens, 146. 

necessary to digestion, 182. 

in plants, 56. 

oxidation, of, 300. 

of plants and seeds, how em- 
ployed, 140. 

its source, 127. 

product of. greatest, how ef- 
fected, 2i34. 

production of, the object of 
agriculture, 141. 

protoxide of, 55. 

replaced, 245. 

transformation of bodies con- 
taining, 269. 

in rice, 139. 

in solid excrements, 139. 

in urine, 137. 

in uric acid, 239. 
Nutrition, conditions essential to, 89. 

explained, 111. 

inorganic substances required, 
90. 

superfluous, how employed, 
107. 

of young plants, 217. 

0AK8, ashes of, 198. 

excretions of, 78. 

dwarf, 106. 
Oak-iDOod affords hnmic acid, 63. 

composition of, 99. 

mouldered, analysis of, 100. 
Odor of substances, 312. 

of gaseous contagious matters, 
374. 
(Enanthic ether, 306. 
Oil of brandy, 310. 

of potatoes, 307. 

of turpentine, composition of, 
123. 

volatile from potatoes, 115. 
Oils, chemical nature of, 55. 
Opium, acids, &c. in, 155, 
Orcin, 288. 

Organs of excretion, 113. 
Organic acids, 55. 

bases, 56. 



Organic acids, chemical decompo- 
sition of, 251. 

chemistry, 53. 

compounds, 123. 

compared with inorganic, 262. 

salts in plants, 150. 
Organized bodies do not generate 

substances, 109. 
Oxalis, genus requiring potash, 93. 
Oxamide, decomposition of, 354. 
Oxide of carbon formed, 267. 
Oxides, metallic in fir-wood, 04. 

quantity of in soils, how in- 
fluenced, 150. 

reduction of, 255. 
Oxygen acids, 35. 

action on alcohol, 290. 

absorbed by oils, 290. 

absorption of at night, 83. 

by leaves, 80. 

respiration, 113. 

plants, 79. 

• wood, 81. 

action upon woody fibre, 95. 

its action in decomposition, 
295. 

bases, 35. 

emitted by leaves, 72. 

exhalation of influenced, 75. 

given to air by land, 121. 

extracted from air by mould,97. 

in air, 70. 

consumption of, 416. 

in water, 84. 

promotes decay, 172. 

quantity consumed, 70. 

replaced, 72. 

returned to the air, 125. 

separated during formation of 
acids, 123. 

with carbonic acid and 

zinc, 125. 

Painter's colic, 345. 

Peat compost, 160, 413. 

analysis of, 230. 

ashes of, 230. 
Pelargoniums, effect of chlorine 

upon, 143. 
Perennial plants, how nourished, 178. 
Peroxide of liijdrogen, 2.54. 
Petersen and Schodler, their analysis 

of woods, 82. 
Phosphate of lime in roots, 93. 

in soils. Dr. Dana's opinion 
of, 412. 

magnesia in seeds, 93. 



PLA 



431 



PUS 



Phosphates in seeds, 200. 
Phosphoric acid in ashes of plants, 
200. 
source of, 200. 
Physician, duty of in case of poison, 

344. 
Physiologists, their experiments not 
satisfactory , 92. 
neglect of chemistry b}', 86. 
Physiology, object of experiments in, 

08. 
Pinus allies, absorbs oxygen, 80. 
Pine apple, effect of cultivation on, 

183. 
Pine trees, ashes of, 1 51 . 

of America, 199. 
Pipe clay, ammonia in, 145. 
Plants, absorb oxygen, 79. 

ashes of, salts in, 150. 
conditions necessary for their 

life, 89. 
contain carbon, 54. 
decay of, a source of oxygen, 

125. 
decompose carbonic acid, 72. 
development of, requisites 

for, 56, 157, 179, 186. 
effect of on rocks, 195. 
elements of, 53. 
emit acetic acid, 194. 
exhalation of carbonic acid 

from, 84. 
of a former world, 117. 
formation of their components, 

124. 
functions of, 77. 
improve the air, 77. 
indifferent substances of, 56. 
influence of gases on, 79. 

of shade, 79. 

inorganic constituents of, 147. 
life of connected vpith that of 
animal, 73. 

its products, 78. 

milky-juiced in barren soil, 

118. 
organic acids in, 148. 

salts in, 1.50. 

perennial nourished, 178. 

products of vary, 183. 

size of proportioned to organs 

of nourishment, 107. 
succession of, its advantage, 

216. 
precautions in cultivat- 
ing, 216. 
vital process in, 125. 



Plants, vital processes of, 212. 

when injurious to each other, 
2U5. 

wild, obtain nitrogen from air, 
141. 

yield oxygen, 84. 
Platinum, does not decompose nitric 

acid, 253. 
Ploughing, its use, 173. 
Poisons, 355. 

generated by disease, 352. 

inorganic, 340. 

peculiar class of, 346. 

rendered inert by heat, 353. 
Poisoning, superficial, 341. 

from sausages, 350. 
Pollen of pinus abies, contains phos- 
phate of lime, 412. 
Pompeii, air from, 70. 

bones from, 203. 
Poplars after pines, 199. 
Potash, action of upon mould, 97. 

in grapes, 153. 

ley of, its effect on excre- 
ments, 140. 

presence of in plants account- 
ed for, 193. 

replaced by soda, 200. 

required by plants, 93, 200. 

quantity in soils, 192. 

saliculite of, 289. 

sihcate of, in soils, 93. 

sources of, 162. 
Potassium, its affinity for oxygen, 

291. 
Potatoes, analysis of, 154. 

oil of, 116,307. 

effect of as food, 183. 

germination of, 176. 

produce of increased, 177. 
Potato brandy, 308. 

starch, action of nitric acid 
on, 86. 
Precipitation, 21. 
Predisposing affinity, 24. 
Preservation of animal food, 294 
Priestley and others on assimilation 

of carbon, 85. 
Processes, chemical, in nature, 53. 
Products of transformations, 109. 
Properties of bodies, 2. 

chemical, 8. 
Projjortions, chemical, 121. 

laws of, 32. 

theory of, 36. 
Prussic arid, 110. 
Pus, globules in, 362. 



SAL 



432 



SOI 



Purgative effect of salts, explained, 

33'j. 
rutrefaction, 94, 259. 
of animals, 219. 
communicated, 3.52. 
induced, 293. 
removes oxygen, 72. 
source of ammonia, 129. 

of carbonic acid, 140. 

Putrefying sausages, death from, 
351. 
their mode of action, 359. 
substances, effect of upon 
wounds, 349. 

may act as medicines, 

360. 

alkaline, 361. 

acid, 362. 

Pyrogallic acid, experiments in, 288. 

qumiNE, 232. 

Rain-water, alkali extracted by, 

194. 
Reduction of oxides, 255. 
Heeds and canes require silica, 200. 
Removal of branches, effect of, 174. 
Reservoirs of dung, 237. 
Rhine, soils in its vicinity, 214. 

wines, 307. 
Riessling grapes, 308. 
Ripening of fruit, 175. 
Rockii, effect of plants on, 195. 
Root secretions, 411. 
Roots, absorb, 147. 

emit extractive matter, 208. 

their office, 167. 

SACHULMIN, 263. 
Saliculite of potash, 289. 
Saline plants, 163. 
Salsola kali, 154. 
SaZ<, what, 110. 

upon leaves, 165. 

volatilization of, 166. 
Salts, acid, 48. 

absorption of, 157. 

basic, 47. 

chlorine, 50. 

common, its effect on poisons, 
344. 

of copper, 246. 

double, 47. 

effect of, on the organism, 
337. 

effect of, on flesh, 338. 

on the stomach, 339. 



Salts, fluorine, 50. 

halhydrate, 48. 

haloid, 51. 

neutral, 49. 

organic in plants, 1.50. 

in the blood, 337. 

oxygen, 46. 

sulphur, 50. 

theory of their constilution, 
46. 

passage of, through the lungs, 
337. 
Salt-works, loss in, 166. 
Saltwort, 93. 
Sand, plants in, 118. 
Sandy soil, decay of wood in, 102. 
Sap, ascending, dissolves sugar, 181. 
Saturating capacity of acids, 47. 
Sausages, poisonous, 350. 
Saussure, his experiments on air, 71. 

on growth of plants, 203. 
Saiodust, changes in, 326. 
Scales of thermometers, correspond- 
ing, 419. 
Schilbler, his observations on rain, 

132. 
Sea-water, analysis of, 166. 

contains carbon, 74. 

requires iodine, 168. 
Seeds, substance of, its use, 105. 

of grapes, constituents of, 148. 

follow man, 162. 
Shade, its effect, 75. 
Silica, in grasses, 158. 

in reeds and canes, 200. 

in soils and springs, 215. 
Silicate of potash, in plants, 93. 

in wheat, 198. 
Siliceous sinter, 215. 
Silicic acid, 21.5. 

Silver, carbonate of, action of organ- 
ic acids on, 256. 

salts of, poisonous effect of, 
244. 
Sinapis alba, 376. 
Size of plants proportional to organs 

of nourishment, 107. 
Smell, what, 374. 
Snow-water, ammonia in, 132. 
Soda, may replace potash, 200. 
Soils, advantage of loosening, 106, 
172 

best for meadow land, 159. 

carbon restored to, 116. 

chemical nature of, its influ- 
ence, 213. 

constituents of, 190. 



SUG 



433 



TOB 



Soi75, exhaustion of, 196. 

ferruginous, improved, 144, 

fertile, of Vesuvius, J93. 

fertility of, influence, 141. 

from lava, 194. 

heavy, retain water, 102. 

imbibe ammonia, 141. 

improved by crops, 206. 

impoverished by, 206. 

nature of its influence, 150. 

necessary to plants, 56. 

of South America, manure for, 
244. 

varieties of, 191. 

of Virginia, 196. 
Solution, 7. 

saturated, 16. 
Specific weights, 3. 
Spontaneous combustion, 287. 
Springs, carbonic acid from, 126, 331. 

containing ammonia, 133. 

of Iceland, and the Azores, 
215. 

quantity of geine in, 59. 
Stagnant water, effect of, 172. 
Stalactites in caverns, 170. 
Starch, accumulation of, in plants, 
177 

composition of, 123. 

contains amylum, 86. 

development of plants influ- 
enced by, 177. 

effect of, on malt, 114. 

product of the life of plants, 78. 

products from, 176. 

in trees, 175. 

in willows, chanffes in the, 
176. ^ 

Staunton, Sir G.,on Chinese manure, 

241. 
Steam, decomposed, 266. 
Stimulants, to plants, 143. 
St. Michael, island of, 215. 
Stomach, calves', experiment with, 
114. 

its power, 349. 
Straw, analysis of, 68. 

carbon in, 68. 
Struve, experiments of, 195. 
Substitution of Oases, 149. 
Succinic a-id, 104. 
Sugar, action of alkalies upon, 265. 

acids upon, 264. 

alcohol from, 45. 

amorphous, 258. 

analysis of. 275. 

carbon in, 67. 

37 



Sugar, composition of, 123. 

crystallized, 25S. 

development of plants, influ- 
ence on, 177. 

fermentation of, 275. 

formula for, 263. 

of maple trees, 180. « 

hydrogen of, 276. 

maximum of, in beet roots, 184. 

metamorphosis of, 276. 

organic compounds calculated 
from, 264. 

product of the life of plants, 78. 

transt'ormalion of, 268. 

when produced, 108. 
Sugar-cane, disappearance of its su- 
gar, 177. 
Sulphur, acidified, 93. 

cry!*taliized, 258. 

salts, 50. 
Svlphuret, what, 13. 
Sulpuretted hydrogen, 112, 
Suh)huric acid, saturating power of, 
47. 

action of on soils, 247. 

lemonade, use of, 345. 
Sulphurous acid arrests decay, 102. 
Sicamp muck, 231. 
Sioine, urine of, 245. 
Synapsis, 376. 

TJiBASHEER,A\\. 

Table of Hessian & English weights, 

416. 
Tannic acid, 123. 
Tartaric acid, 123. 

converted into sugar, 124. 

in wines, 307. 
Tcltoioa turnip, 107, 184. 
Temperature, 9. 

its influence, 23. 
Tension of bodies, 6. 
Thinard, his experiments on yeast, 

279. 
Theory, atomic, 38. 

of chemical proportions, 36. 

of salts, 46. 
Thermometer, 10. 
Thermometers, corresponding scales 

of, 419. 
Thomson, his opinion respecting hu- 
mus, 58. 
Tin, action on nitric acid, 253. 
Toiflcco, juice contains ammonia, 135 

leaves of, 31 1. 

nitric acid in, 138. 

in Virginia, 196. 



VEG 



434 



WOO 



Tobacco, and wheat, 205. 
Transformriiion by heat, 267. 

chemical, 109, 149. 

differ from decomposi- 
tions, 112. 

of acetic acid, 267. 

of arragonite, 258. 

of carbonic acid, 186. 

of nieconic acid, 267. 

not affected by the vital prin- 
ciple, 114. 

explained, 114. 

of bodies containing nitrogen, 

results of, 116. 

peculiar, in plants, 108. 

of wood, 2G8. 

of cyanic acid, 271. 

of cyanogen, 272. 

of gluten, 304. 
Transjdantalion, effect of, 174. 
Trees, diseases of. 181. 

require alkalies, 198. 
Turnip, small, 107. 
Turpentine, oil of, 123. 

Vlmin, 57 

Union of gases, 39. 

Urea, 127. 

converted into carbonate of 
ammonia, 138. 

in urine, 236. 
Uric acid, contains ammonia, 239. 

transformations of, 229. 
Urinary calculi, treatment of, 114. 

organs eliminate nitrogen, 113 
Urine, contains nitrogen, 137. 

its use as manure, 137, 235. 

of men, &c., 138. 

of horses, 143. 

analysis of, 144. 

human, analysis of, 236. 

of cows, 222. 

its use in Flanders, 241. 

of swine, 245. 

VACCINATION, its effect, 372. 

Vapors, what, G, 12. 

Vegetables, contain hydrogen, 122. 

nutrition of, chemical proces- 
ses in the, 53 

supply carbonic acid to water, 
85. 

vital activity of, 190. 
Vegetable albumen, 137. 

mould, 97. 
Vegetable inices, fermentation of, 276. 



Vesuvius, fertile soil of, 193. 
Vines, effect of manure on, 161. 

juice of, yields ammonia, 135. 
Vinous fermentation, 303. 
Virginia, early products of its soil, 

196. 
Virus of smallpox, »&c., 352. 

vaccine, 302. 
Vitality, what, 90. 
Vital principle, 113, 357. 

value of the term, 115. 

how balanced in the blood, 
372. 
Vital process in plants, 125, 
Vital processes of plants, 212. 
Volume, 2. 

connexion of, with atomic 
weight, 41. 
Volumes, theory of, 41. 

Water, carbonic acid of, absorbed, 
85. 

composition of, 123. 

dissolves mould, 97. 

of crystallization, 20. 

effect of, 284. 

from ammonia, 302. 

plants, their action, 85. 

rain, carbon conveyed by, 66. 

contains ammonia, 146. 

required by plants, 56, 

120. 

required by gypsum, 144. 

salt, analysis of, 166. 
WaveUitc, 201. 
Wax in plants, its use, 118. 
Weight, atomic, 39. 

connexion of, with volume, 
41. 

specific, 3. 

of gases, 42. 

Wheat, analysis of, 199. 

ashes of, 203. 

exhausts, 197. 

gluten of, 136. 

and tobacco, 205. 

why it does not thrive, 198. 

in Virginia, 196. 
Willows, growth of, 176. 
Wine, effect of gluten upon, 313. 

fermentation of, 306. 

properties of, 313. 

substances in, 306. 

taste and smell of, 307. 

varieties of, 307. 
Winter, early, its effect, 161. 
Wood, decomposition of, 283. 



woo 



435 



ZIN 



Wood charcoal, may replace humus, 
118. 

decayed, combustion of, 103. 

absorbs ammonia, 14G. 

absorbs oxygen, 81. 

analysis of, 82. 

carbon in, 67. 

conversion of, into humus, 95. 

decay of, 101. 

requires air, 96. 

in sandy soil, 102. 

decomposition of, 250, 283. 

effect of moisture and air, 99. 

elements of, 101. 

formation of, 181. 

oak, mouldering, 82. 

ripening of, 176 

source of its carbon, 68. 

transformation of, 268. 
Wood-coal, 325. 

how produced, 327. 

analysis of, 328. 
Wood-cutters, their privilege, 160. 
Woody fibre, carbon in, 77. 

changes in, 325. 

composition of, 123. 



Woody fibre, decomposition of, 98. 

difference between it and 

wood, 82. 
formation of, 77. 
moist evolves carbonic acid, 

289. 
mould from, 98. 
phenomena attending its de- 
cay, 95. 
Wormwood, effect of its culture, 

161. 
Wort, fermentation of, 305. 
Wounds, effect of putrefying sub- 
stances on, 349. 

VeaST, 277. 

destroyed, 306. 
experiments on, 279. 
formed, 306. 
its mode of action, 279. 
its action arrested , 309. 
its production, 348. 

ZINC, decomposition of water with, 
125. 



ERRATA. 

Page 53, line 3, after Agriculture insert and Physiology 

" 58, " 32, " alkalies " and with lime 

" 69, " 24, for Dr. Dana has given read Prof. Hitchcock has given. 

The refeieiic in the note on page 407, should be to Dr. Dana's Table, page 402. 



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